diff --git a/.github/workflows/coding-standards.yml b/.github/workflows/coding-standards.yml
index 64e4a12..261e377 100644
--- a/.github/workflows/coding-standards.yml
+++ b/.github/workflows/coding-standards.yml
@@ -37,3 +37,9 @@ jobs:
 
       - name: "Run PHP CS Fixer"
         run: "vendor/bin/php-cs-fixer fix --verbose --dry-run"
+
+      - name: "Install PHPUnit for PHPStan"
+        run: "php vendor/bin/simple-phpunit install"
+
+      - name: "Run PHPStan"
+        run: "php vendor/bin/phpstan analyse --no-progress"
diff --git a/composer.json b/composer.json
index 135988e..eb29e2b 100644
--- a/composer.json
+++ b/composer.json
@@ -40,6 +40,10 @@
     },
     "require-dev": {
         "friendsofphp/php-cs-fixer": "^3.0",
+        "phpstan/extension-installer": "^1.1",
+        "phpstan/phpstan": "^1.2",
+        "phpstan/phpstan-deprecation-rules": "^1.0",
+        "phpstan/phpstan-phpunit": "^1.0",
         "symfony/phpunit-bridge": "^6.0"
     },
     "config": {
diff --git a/lib/Imgur/Api/AbstractApi.php b/lib/Imgur/Api/AbstractApi.php
index 57a6b3b..fbf7120 100644
--- a/lib/Imgur/Api/AbstractApi.php
+++ b/lib/Imgur/Api/AbstractApi.php
@@ -14,12 +14,12 @@
 abstract class AbstractApi
 {
     /**
-     * @var \Imgur\Client
+     * @var Client
      */
     protected $client;
 
     /**
-     * @var \Imgur\Pager\PagerInterface
+     * @var PagerInterface
      */
     protected $pager;
 
@@ -31,16 +31,12 @@ public function __construct(Client $client, PagerInterface $pager = null)
 
     /**
      * Perform a GET request and return the parsed response.
-     *
-     * @param string $url
-     *
-     * @return array
      */
-    public function get($url, $parameters = [])
+    public function get(string $url, array $parameters = []): array
     {
         $httpClient = $this->client->getHttpClient();
 
-        if (!empty($this->pager)) {
+        if (null !== $this->pager) {
             $parameters['page'] = $this->pager->getPage();
             $parameters['perPage'] = $this->pager->getResultsPerPage();
         }
@@ -52,12 +48,8 @@ public function get($url, $parameters = [])
 
     /**
      * Perform a POST request and return the parsed response.
-     *
-     * @param string $url
-     *
-     * @return array
      */
-    public function post($url, $parameters = [])
+    public function post(string $url, array $parameters = []): array
     {
         $httpClient = $this->client->getHttpClient();
 
@@ -68,12 +60,8 @@ public function post($url, $parameters = [])
 
     /**
      * Perform a PUT request and return the parsed response.
-     *
-     * @param string $url
-     *
-     * @return array
      */
-    public function put($url, $parameters = [])
+    public function put(string $url, array $parameters = []): array
     {
         $httpClient = $this->client->getHttpClient();
 
@@ -84,12 +72,8 @@ public function put($url, $parameters = [])
 
     /**
      * Perform a DELETE request and return the parsed response.
-     *
-     * @param string $url
-     *
-     * @return array
      */
-    public function delete($url, $parameters = [])
+    public function delete(string $url, array $parameters = []): array
     {
         $httpClient = $this->client->getHttpClient();
 
@@ -101,10 +85,9 @@ public function delete($url, $parameters = [])
     /**
      * Validate "sort" parameter and throw an exception if it's a bad value.
      *
-     * @param string $sort           Input value
-     * @param array  $possibleValues
+     * @param string $sort Input value
      */
-    protected function validateSortArgument($sort, $possibleValues)
+    protected function validateSortArgument(string $sort, array $possibleValues): void
     {
         $this->validateArgument('Sort', $sort, $possibleValues);
     }
@@ -112,10 +95,9 @@ protected function validateSortArgument($sort, $possibleValues)
     /**
      * Validate "window" parameter and throw an exception if it's a bad value.
      *
-     * @param string $window         Input value
-     * @param array  $possibleValues
+     * @param string $window Input value
      */
-    protected function validateWindowArgument($window, $possibleValues)
+    protected function validateWindowArgument(string $window, array $possibleValues): void
     {
         $this->validateArgument('Window', $window, $possibleValues);
     }
@@ -123,10 +105,9 @@ protected function validateWindowArgument($window, $possibleValues)
     /**
      * Validate "vote" parameter and throw an exception if it's a bad value.
      *
-     * @param string $vote           Input value
-     * @param array  $possibleValues
+     * @param string $vote Input value
      */
-    protected function validateVoteArgument($vote, $possibleValues)
+    protected function validateVoteArgument(string $vote, array $possibleValues): void
     {
         $this->validateArgument('Vote', $vote, $possibleValues);
     }
@@ -138,7 +119,7 @@ protected function validateVoteArgument($vote, $possibleValues)
      * @param string $input          Input value
      * @param array  $possibleValues Possible values for this argument
      */
-    private function validateArgument($type, $input, $possibleValues)
+    private function validateArgument(string $type, string $input, array $possibleValues): void
     {
         if (!\in_array($input, $possibleValues, true)) {
             throw new InvalidArgumentException($type . ' parameter "' . $input . '" is wrong. Possible values are: ' . implode(', ', $possibleValues));
diff --git a/lib/Imgur/Api/Account.php b/lib/Imgur/Api/Account.php
index 33656a4..27ff5a6 100644
--- a/lib/Imgur/Api/Account.php
+++ b/lib/Imgur/Api/Account.php
@@ -31,7 +31,7 @@ public function base($username = 'me')
      *
      * @param string $username
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function deleteAccount($username)
     {
@@ -106,7 +106,7 @@ public function settings($username = 'me')
      *
      * @see https://api.imgur.com/endpoints/account#update-settings
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function changeAccountSettings($parameters)
     {
@@ -147,7 +147,7 @@ public function accountGalleryProfile($username = 'me')
      *
      * @see https://api.imgur.com/endpoints/account#verify-email
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function verifyUsersEmail($username = 'me')
     {
@@ -161,7 +161,7 @@ public function verifyUsersEmail($username = 'me')
      *
      * @see https://api.imgur.com/endpoints/account#send-verify-email
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function sendVerificationEmail($username = 'me')
     {
@@ -207,7 +207,7 @@ public function album($albumId, $username = 'me')
      *
      * @see https://api.imgur.com/endpoints/account#album-ids
      *
-     * @return array<int>
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function albumIds($username = 'me', $page = 0)
     {
@@ -221,7 +221,7 @@ public function albumIds($username = 'me', $page = 0)
      *
      * @see https://api.imgur.com/endpoints/account#album-count
      *
-     * @return int
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function albumCount($username = 'me')
     {
@@ -236,7 +236,7 @@ public function albumCount($username = 'me')
      *
      * @see https://api.imgur.com/endpoints/account#album-delete
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function albumDelete($albumId, $username = 'me')
     {
@@ -286,7 +286,7 @@ public function comment($commentId, $username = 'me')
      *
      * @see https://api.imgur.com/endpoints/account#comment-ids
      *
-     * @return array<int>
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function commentIds($username = 'me', $page = 0, $sort = 'newest')
     {
@@ -302,7 +302,7 @@ public function commentIds($username = 'me', $page = 0, $sort = 'newest')
      *
      * @see https://api.imgur.com/endpoints/account#comment-count
      *
-     * @return int
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function commentCount($username = 'me')
     {
@@ -317,7 +317,7 @@ public function commentCount($username = 'me')
      *
      * @see https://api.imgur.com/endpoints/account#comment-delete
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function commentDelete($commentId, $username = 'me')
     {
@@ -364,7 +364,7 @@ public function image($imageId, $username = 'me')
      *
      * @see https://api.imgur.com/endpoints/account#image-ids
      *
-     * @return array<int>
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function imageIds($username = 'me', $page = 0)
     {
@@ -378,7 +378,7 @@ public function imageIds($username = 'me', $page = 0)
      *
      * @see https://api.imgur.com/endpoints/account#image-count
      *
-     * @return int
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function imageCount($username = 'me')
     {
@@ -393,7 +393,7 @@ public function imageCount($username = 'me')
      *
      * @see https://api.imgur.com/endpoints/account#image-delete
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function imageDelete($deleteHash, $username = 'me')
     {
diff --git a/lib/Imgur/Api/Album.php b/lib/Imgur/Api/Album.php
index f96d8ff..cfbf75a 100644
--- a/lib/Imgur/Api/Album.php
+++ b/lib/Imgur/Api/Album.php
@@ -64,7 +64,7 @@ public function albumImage($albumId, $imageId)
      *
      * @see https://api.imgur.com/endpoints/album#album-upload
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function create($data)
     {
@@ -80,7 +80,7 @@ public function create($data)
      *
      * @see https://api.imgur.com/endpoints/album#album-update
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function update($deletehashOrAlbumId, $data)
     {
@@ -96,7 +96,7 @@ public function update($deletehashOrAlbumId, $data)
      *
      * @see https://api.imgur.com/endpoints/album#album-delete
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function deleteAlbum($deletehashOrAlbumId)
     {
@@ -110,7 +110,7 @@ public function deleteAlbum($deletehashOrAlbumId)
      *
      * @see https://api.imgur.com/endpoints/album#album-favorite
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function favoriteAlbum($albumId)
     {
@@ -125,7 +125,7 @@ public function favoriteAlbum($albumId)
      *
      * @see https://api.imgur.com/endpoints/album#album-set-to
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function setAlbumImages($albumId, array $imageIds)
     {
@@ -140,7 +140,7 @@ public function setAlbumImages($albumId, array $imageIds)
      *
      * @see https://api.imgur.com/endpoints/album#album-add-to
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function addImages($albumId, array $imageIds)
     {
@@ -155,7 +155,7 @@ public function addImages($albumId, array $imageIds)
      *
      * @see https://api.imgur.com/endpoints/album#album-remove-from
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function removeImages($deletehashOrAlbumId, array $imageIds)
     {
diff --git a/lib/Imgur/Api/Comment.php b/lib/Imgur/Api/Comment.php
index 20a5bcb..827e635 100644
--- a/lib/Imgur/Api/Comment.php
+++ b/lib/Imgur/Api/Comment.php
@@ -34,7 +34,7 @@ public function comment($commentId)
      *
      * @see https://api.imgur.com/endpoints/comment#comment-create
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function create($data)
     {
@@ -52,7 +52,7 @@ public function create($data)
      *
      * @see https://api.imgur.com/endpoints/comment#comment-delete
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function deleteComment($commentId)
     {
@@ -81,7 +81,7 @@ public function replies($commentId)
      *
      * @see https://api.imgur.com/endpoints/comment#comment-reply-create
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function createReply($commentId, $data)
     {
@@ -100,7 +100,7 @@ public function createReply($commentId, $data)
      *
      * @see https://api.imgur.com/endpoints/comment#comment-vote
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function vote($commentId, $vote)
     {
@@ -116,7 +116,7 @@ public function vote($commentId, $vote)
      *
      * @see https://api.imgur.com/endpoints/comment#comment-report
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function report($commentId)
     {
diff --git a/lib/Imgur/Api/Conversation.php b/lib/Imgur/Api/Conversation.php
index 90b3327..432ed9b 100644
--- a/lib/Imgur/Api/Conversation.php
+++ b/lib/Imgur/Api/Conversation.php
@@ -47,7 +47,7 @@ public function conversation($conversationId)
      *
      * @see https://api.imgur.com/endpoints/conversation#message-create
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function messageCreate($data)
     {
@@ -65,7 +65,7 @@ public function messageCreate($data)
      *
      * @see https://api.imgur.com/endpoints/conversation#message-delete
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function conversationDelete($conversationId)
     {
@@ -79,7 +79,7 @@ public function conversationDelete($conversationId)
      *
      * @see https://api.imgur.com/endpoints/conversation#message-report
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function reportSender($username)
     {
@@ -93,7 +93,7 @@ public function reportSender($username)
      *
      * @see https://api.imgur.com/endpoints/conversation#message-block
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function blockSender($username)
     {
diff --git a/lib/Imgur/Api/CustomGallery.php b/lib/Imgur/Api/CustomGallery.php
index 77a6967..2adf684 100644
--- a/lib/Imgur/Api/CustomGallery.php
+++ b/lib/Imgur/Api/CustomGallery.php
@@ -66,7 +66,7 @@ public function image($imageId)
      *
      * @see https://api.imgur.com/endpoints/custom_gallery#custom-gallery-add
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function addTags(array $tags)
     {
@@ -78,7 +78,7 @@ public function addTags(array $tags)
      *
      * @see https://api.imgur.com/endpoints/custom_gallery#custom-gallery-remove
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function removeTags(array $tags)
     {
@@ -92,7 +92,7 @@ public function removeTags(array $tags)
      *
      * @see https://api.imgur.com/endpoints/custom_gallery#filtered-out-block
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function blockTag($tag)
     {
@@ -106,7 +106,7 @@ public function blockTag($tag)
      *
      * @see https://api.imgur.com/endpoints/custom_gallery#filtered-out-unblock
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function unBlockTag($tag)
     {
diff --git a/lib/Imgur/Api/Gallery.php b/lib/Imgur/Api/Gallery.php
index dd0a999..88e24e7 100644
--- a/lib/Imgur/Api/Gallery.php
+++ b/lib/Imgur/Api/Gallery.php
@@ -169,7 +169,7 @@ public function galleryItemTags($imageOrAlbumId)
      *
      * @see https://api.imgur.com/endpoints/gallery#gallery-tag-vote
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function galleryVoteTag($id, $name, $vote)
     {
@@ -220,7 +220,7 @@ public function randomGalleryImages($page = 0)
      *
      * @see https://api.imgur.com/endpoints/gallery#to-gallery
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function submitToGallery($imageOrAlbumId, $data)
     {
@@ -238,7 +238,7 @@ public function submitToGallery($imageOrAlbumId, $data)
      *
      * @see https://api.imgur.com/endpoints/gallery#from-gallery
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function removeFromGallery($imageOrAlbumId)
     {
@@ -280,7 +280,7 @@ public function image($imageId)
      *
      * @see https://api.imgur.com/endpoints/gallery#gallery-reporting
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function report($imageOrAlbumId)
     {
@@ -309,7 +309,7 @@ public function votes($imageOrAlbumId)
      *
      * @see https://api.imgur.com/endpoints/gallery#gallery-voting
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function vote($imageOrAlbumId, $vote)
     {
@@ -358,7 +358,7 @@ public function comment($imageOrAlbumId, $commentId)
      *
      * @see https://api.imgur.com/endpoints/gallery#gallery-comment-creation
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function createComment($imageOrAlbumId, $data)
     {
@@ -378,7 +378,7 @@ public function createComment($imageOrAlbumId, $data)
      *
      * @see https://api.imgur.com/endpoints/gallery#gallery-comment-reply
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function createReply($imageOrAlbumId, $commentId, $data)
     {
@@ -396,7 +396,7 @@ public function createReply($imageOrAlbumId, $commentId, $data)
      *
      * @see https://api.imgur.com/endpoints/gallery#gallery-comment-ids
      *
-     * @return array<int>
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function commentIds($imageOrAlbumId)
     {
@@ -410,7 +410,7 @@ public function commentIds($imageOrAlbumId)
      *
      * @see https://api.imgur.com/endpoints/gallery#gallery-comment-count
      *
-     * @return int
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function commentCount($imageOrAlbumId)
     {
diff --git a/lib/Imgur/Api/Image.php b/lib/Imgur/Api/Image.php
index 50e8ae2..a085ad0 100644
--- a/lib/Imgur/Api/Image.php
+++ b/lib/Imgur/Api/Image.php
@@ -35,7 +35,7 @@ public function image($imageId)
      *
      * @see https://api.imgur.com/endpoints/image#image-upload
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function upload($data)
     {
@@ -63,7 +63,7 @@ public function upload($data)
      *
      * @see https://api.imgur.com/endpoints/image#image-delete
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function deleteImage($imageIdOrDeleteHash)
     {
@@ -80,7 +80,7 @@ public function deleteImage($imageIdOrDeleteHash)
      *
      * @see https://api.imgur.com/endpoints/image#image-update
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function update($imageIdOrDeleteHash, $data)
     {
@@ -94,7 +94,7 @@ public function update($imageIdOrDeleteHash, $data)
      *
      * @see https://api.imgur.com/endpoints/image#image-favorite
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function favorite($imageIdOrDeleteHash)
     {
diff --git a/lib/Imgur/Api/Notification.php b/lib/Imgur/Api/Notification.php
index c412954..2d9f136 100644
--- a/lib/Imgur/Api/Notification.php
+++ b/lib/Imgur/Api/Notification.php
@@ -20,10 +20,8 @@ class Notification extends AbstractApi
      *
      * @return array With keys "replies" & "messages"
      */
-    public function notifications($new = true)
+    public function notifications(string $new = 'true')
     {
-        $new = $new ? 'true' : 'false';
-
         return $this->get('notification', ['new' => $new]);
     }
 
@@ -48,7 +46,7 @@ public function notification($notificationId)
      *
      * @see https://api.imgur.com/endpoints/notification#notification-viewed
      *
-     * @return bool
+     * @return array (@see https://api.imgur.com/models/basic)
      */
     public function notificationViewed($notificationId)
     {
diff --git a/lib/Imgur/Api/Topic.php b/lib/Imgur/Api/Topic.php
index df484bc..bd078c7 100644
--- a/lib/Imgur/Api/Topic.php
+++ b/lib/Imgur/Api/Topic.php
@@ -45,7 +45,7 @@ public function galleryTopic($topicId, $sort = 'viral', $page = 0, $window = 'we
      * View a single item in a gallery topic.
      *
      * @param string $topicId The ID or URL-formatted name of the topic. If using a topic's name, replace its spaces with underscores (Mother's_Day)
-     * @param int    $itemId  The ID for the gallery item
+     * @param string $itemId  The ID for the gallery item
      *
      * @see https://api.imgur.com/endpoints/topic#gallery-topic-item
      *
diff --git a/lib/Imgur/Auth/AuthInterface.php b/lib/Imgur/Auth/AuthInterface.php
index d11d71a..79fda82 100644
--- a/lib/Imgur/Auth/AuthInterface.php
+++ b/lib/Imgur/Auth/AuthInterface.php
@@ -14,20 +14,18 @@ interface AuthInterface
      *
      * @param string $responseType (code, token, pin) Determines if Imgur should return an authorization_code, a PIN code, or an opaque access_token
      * @param string $state        Any value which you want Imgur to pass back
-     *
-     * @return string
      */
-    public function getAuthenticationUrl($responseType = 'code', $state = null);
+    public function getAuthenticationUrl(string $responseType = 'code', string $state = null): string;
 
-    public function getAccessToken();
+    public function getAccessToken(): ?array;
 
-    public function requestAccessToken($code, $responseType);
+    public function requestAccessToken(string $code, string $requestType = null): array;
 
-    public function setAccessToken($accessToken);
+    public function setAccessToken(array $accessToken): void;
 
-    public function sign();
+    public function sign(): void;
 
-    public function refreshToken();
+    public function refreshToken(): array;
 
-    public function checkAccessTokenExpired();
+    public function checkAccessTokenExpired(): bool;
 }
diff --git a/lib/Imgur/Auth/OAuth2.php b/lib/Imgur/Auth/OAuth2.php
index 38752e5..d06a21b 100644
--- a/lib/Imgur/Auth/OAuth2.php
+++ b/lib/Imgur/Auth/OAuth2.php
@@ -32,7 +32,7 @@ class OAuth2 implements AuthInterface
     /**
      * The class handling communication with Imgur servers.
      *
-     * @var \Imgur\HttpClient\HttpClientInterface
+     * @var HttpClientInterface
      */
     private $httpClient;
 
@@ -61,11 +61,8 @@ class OAuth2 implements AuthInterface
 
     /**
      * Instantiates the OAuth2 class, but does not trigger the authentication process.
-     *
-     * @param string $clientId
-     * @param string $clientSecret
      */
-    public function __construct(HttpClientInterface $httpClient, $clientId, $clientSecret)
+    public function __construct(HttpClientInterface $httpClient, string $clientId, string $clientSecret)
     {
         $this->clientId = $clientId;
         $this->clientSecret = $clientSecret;
@@ -74,13 +71,8 @@ public function __construct(HttpClientInterface $httpClient, $clientId, $clientS
 
     /**
      * Generates the authentication URL to which a user should be pointed at in order to start the OAuth2 process.
-     *
-     * @param string      $responseType
-     * @param string|null $state
-     *
-     * @return string
      */
-    public function getAuthenticationURL($responseType = 'code', $state = null)
+    public function getAuthenticationURL(string $responseType = 'code', string $state = null): string
     {
         $httpQueryParameters = [
             'client_id' => $this->clientId,
@@ -96,12 +88,9 @@ public function getAuthenticationURL($responseType = 'code', $state = null)
     /**
      * Exchanges a code/pin for an access token.
      *
-     * @param string $code
      * @param string $requestType
-     *
-     * @return array
      */
-    public function requestAccessToken($code, $requestType)
+    public function requestAccessToken(string $code, string $requestType = null): array
     {
         switch ($requestType) {
             case 'pin':
@@ -146,10 +135,8 @@ public function requestAccessToken($code, $requestType)
      * you will have to prompt the user for their login information again.
      *
      * @throws AuthException
-     *
-     * @return array
      */
-    public function refreshToken()
+    public function refreshToken(): array
     {
         $token = $this->getAccessToken();
 
@@ -182,10 +169,8 @@ public function refreshToken()
      * @param array $token
      *
      * @throws AuthException
-     *
-     * @return array
      */
-    public function setAccessToken($token)
+    public function setAccessToken(array $token = null): void
     {
         if (!\is_array($token)) {
             throw new AuthException('Token is not a valid json string.');
@@ -206,33 +191,29 @@ public function setAccessToken($token)
 
     /**
      * Getter for the current access token.
-     *
-     * @return array|null
      */
-    public function getAccessToken()
+    public function getAccessToken(): ?array
     {
         return $this->token;
     }
 
     /**
      * Check if the current access token (if present), is still usable.
-     *
-     * @return bool
      */
-    public function checkAccessTokenExpired()
+    public function checkAccessTokenExpired(): bool
     {
         // don't have the data? Let's assume the token has expired
         if (!isset($this->token['created_at']) || !isset($this->token['expires_in'])) {
             return true;
         }
 
-        return ($this->token['created_at'] + $this->token['expires_in']) < time();
+        return ((int) ($this->token['created_at'] + $this->token['expires_in'])) < time();
     }
 
     /**
      * Add middleware for attaching header signature to each request.
      */
-    public function sign()
+    public function sign(): void
     {
         $this->httpClient->addAuthMiddleware(
             $this->getAccessToken(),
diff --git a/lib/Imgur/Client.php b/lib/Imgur/Client.php
index 02acb04..fdc24dc 100644
--- a/lib/Imgur/Client.php
+++ b/lib/Imgur/Client.php
@@ -2,6 +2,7 @@
 
 namespace Imgur;
 
+use Imgur\Api\AbstractApi;
 use Imgur\Auth\AuthInterface;
 use Imgur\Exception\InvalidArgumentException;
 use Imgur\HttpClient\HttpClient;
@@ -25,14 +26,14 @@ class Client
     /**
      * The class handling communication with Imgur servers.
      *
-     * @var \Imgur\HttpClient\HttpClientInterface
+     * @var HttpClientInterface
      */
     private $httpClient;
 
     /**
      * The class handling authentication.
      *
-     * @var \Imgur\Auth\AuthInterface
+     * @var AuthInterface
      */
     private $authenticationClient;
 
@@ -48,14 +49,11 @@ public function __construct(AuthInterface $authenticationClient = null, HttpClie
     }
 
     /**
-     * @param string                     $name
-     * @param Imgur\Pager\PagerInterface $pager
+     * @param PagerInterface $pager
      *
      * @throws InvalidArgumentException
-     *
-     * @return ApiInterface
      */
-    public function api($name, PagerInterface $pager = null)
+    public function api(string $name, PagerInterface $pager = null): AbstractApi
     {
         if (!$this->getAccessToken()) {
             $this->sign();
@@ -63,16 +61,16 @@ public function api($name, PagerInterface $pager = null)
 
         $apiClass = 'Imgur\\Api\\' . ucfirst($name);
         if (class_exists($apiClass)) {
-            return new $apiClass($this, $pager);
+            /** @var AbstractApi */
+            $api = new $apiClass($this, $pager);
+
+            return $api;
         }
 
         throw new InvalidArgumentException('API Method not supported: "' . $name . '" (apiClass: "' . $apiClass . '")');
     }
 
-    /**
-     * @return HttpClientInterface
-     */
-    public function getHttpClient()
+    public function getHttpClient(): HttpClientInterface
     {
         if (null === $this->httpClient) {
             $this->setHttpClient(new HttpClient($this->options));
@@ -81,19 +79,17 @@ public function getHttpClient()
         return $this->httpClient;
     }
 
-    public function setHttpClient(HttpClientInterface $httpClient)
+    public function setHttpClient(HttpClientInterface $httpClient): void
     {
         $this->httpClient = $httpClient;
     }
 
     /**
-     * @param string $name
-     *
      * @throws InvalidArgumentException
      *
      * @return string
      */
-    public function getOption($name)
+    public function getOption(string $name): ?string
     {
         if (!\array_key_exists($name, $this->options)) {
             throw new InvalidArgumentException(sprintf('Undefined option called: "%s"', $name));
@@ -103,12 +99,11 @@ public function getOption($name)
     }
 
     /**
-     * @param string $name
-     * @param mixed  $value
+     * @param mixed $value
      *
      * @throws InvalidArgumentException
      */
-    public function setOption($name, $value)
+    public function setOption(string $name, $value): void
     {
         if (!\array_key_exists($name, $this->options)) {
             throw new InvalidArgumentException(sprintf('Undefined option called: "%s"', $name));
@@ -119,10 +114,8 @@ public function setOption($name, $value)
 
     /**
      * Retrieves the Auth object and also instantiates it if not already present.
-     *
-     * @return Auth\AuthInterface
      */
-    public function getAuthenticationClient()
+    public function getAuthenticationClient(): AuthInterface
     {
         if (null === $this->authenticationClient) {
             $this->authenticationClient = new Auth\OAuth2(
@@ -138,25 +131,17 @@ public function getAuthenticationClient()
     /**
      * Proxy method for the authentication objects URL building method.
      *
-     * @param string $responseType
      * @param string $state
-     *
-     * @return string
      */
-    public function getAuthenticationUrl($responseType = 'code', $state = null)
+    public function getAuthenticationUrl(string $responseType = 'code', string $state = null): string
     {
         return $this->getAuthenticationClient()->getAuthenticationUrl($responseType, $state);
     }
 
     /**
      * Proxy method for exchanging a code for an access token/a pin for an access token.
-     *
-     * @param string $code
-     * @param string $responseType
-     *
-     * @return string
      */
-    public function requestAccessToken($code, $responseType = 'code')
+    public function requestAccessToken(string $code, string $responseType = 'code'): array
     {
         return $this->getAuthenticationClient()->requestAccessToken($code, $responseType);
     }
@@ -166,37 +151,31 @@ public function requestAccessToken($code, $responseType = 'code')
      *
      * @return array
      */
-    public function getAccessToken()
+    public function getAccessToken(): ?array
     {
         return $this->getAuthenticationClient()->getAccessToken();
     }
 
     /**
      * Proxy method for checking if the access token expired.
-     *
-     * @return array
      */
-    public function checkAccessTokenExpired()
+    public function checkAccessTokenExpired(): bool
     {
         return $this->getAuthenticationClient()->checkAccessTokenExpired();
     }
 
     /**
      * Proxy method for refreshing an access token.
-     *
-     * @return array
      */
-    public function refreshToken()
+    public function refreshToken(): array
     {
         return $this->getAuthenticationClient()->refreshToken();
     }
 
     /**
      * Proxy method for setting an access token.
-     *
-     * @param array $token
      */
-    public function setAccessToken($token)
+    public function setAccessToken(array $token): void
     {
         $this->getAuthenticationClient()->setAccessToken($token);
     }
@@ -204,7 +183,7 @@ public function setAccessToken($token)
     /**
      * Proxy method for signing a request.
      */
-    public function sign()
+    public function sign(): void
     {
         $this->getAuthenticationClient()->sign();
     }
diff --git a/lib/Imgur/Exception/MissingArgumentException.php b/lib/Imgur/Exception/MissingArgumentException.php
index 50a00f3..d95d797 100644
--- a/lib/Imgur/Exception/MissingArgumentException.php
+++ b/lib/Imgur/Exception/MissingArgumentException.php
@@ -4,12 +4,15 @@
 
 class MissingArgumentException extends ErrorException
 {
-    public function __construct($required, $code = 0, $previous = null)
+    /**
+     * @param array|string $required
+     */
+    public function __construct($required, int $code = 0)
     {
         if (\is_string($required)) {
             $required = [$required];
         }
 
-        parent::__construct(sprintf('One or more of required ("%s") parameters is missing!', implode('", "', $required)), $code, $previous);
+        parent::__construct(sprintf('One or more of required ("%s") parameters is missing!', implode('", "', $required)), $code);
     }
 }
diff --git a/lib/Imgur/HttpClient/HttpClient.php b/lib/Imgur/HttpClient/HttpClient.php
index 09d7c20..4c8c71b 100644
--- a/lib/Imgur/HttpClient/HttpClient.php
+++ b/lib/Imgur/HttpClient/HttpClient.php
@@ -9,6 +9,7 @@
 use Imgur\Middleware\AuthMiddleware;
 use Imgur\Middleware\ErrorMiddleware;
 use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\ResponseInterface;
 
 /**
  * Basic client for performing HTTP requests.
@@ -20,7 +21,7 @@ class HttpClient implements HttpClientInterface
     /**
      * The Guzzle instance.
      *
-     * @var \GuzzleHttp\ClientInterface
+     * @var ClientInterface
      */
     protected $client;
 
@@ -33,12 +34,10 @@ class HttpClient implements HttpClientInterface
         'base_url' => 'https://api.imgur.com/3/',
     ];
 
+    /** @var HandlerStack */
     protected $stack;
 
-    /**
-     * @param ClientInterface $client
-     */
-    public function __construct(array $options = [], ClientInterface $client = null)
+    public function __construct(array $options = [], ClientInterface $client = null, HandlerStack $stack = null)
     {
         $this->options = array_merge($options, $this->options);
 
@@ -47,10 +46,7 @@ public function __construct(array $options = [], ClientInterface $client = null)
 
         // during test (at least) handler can be injected into the client
         // so we need to retrieve it to be able to inject our own middleware
-        $this->stack = HandlerStack::create();
-        if (null !== $client) {
-            $this->stack = $client->getConfig('handler');
-        }
+        $this->stack = (null !== $client && null !== $stack) ? $stack : HandlerStack::create();
 
         $this->stack->push(ErrorMiddleware::error());
 
@@ -63,7 +59,7 @@ public function __construct(array $options = [], ClientInterface $client = null)
     /**
      * {@inheritdoc}
      */
-    public function get($url, array $parameters = [])
+    public function get($url, array $parameters = []): ResponseInterface
     {
         return $this->performRequest($url, $parameters, 'GET');
     }
@@ -71,7 +67,7 @@ public function get($url, array $parameters = [])
     /**
      * {@inheritdoc}
      */
-    public function delete($url, array $parameters = [])
+    public function delete($url, array $parameters = []): ResponseInterface
     {
         return $this->performRequest($url, $parameters, 'DELETE');
     }
@@ -79,7 +75,7 @@ public function delete($url, array $parameters = [])
     /**
      * {@inheritdoc}
      */
-    public function post($url, array $parameters = [])
+    public function post($url, array $parameters = []): ResponseInterface
     {
         return $this->performRequest($url, $parameters, 'POST');
     }
@@ -87,7 +83,7 @@ public function post($url, array $parameters = [])
     /**
      * {@inheritdoc}
      */
-    public function put($url, array $parameters = [])
+    public function put($url, array $parameters = []): ResponseInterface
     {
         return $this->performRequest($url, $parameters, 'PUT');
     }
@@ -95,7 +91,7 @@ public function put($url, array $parameters = [])
     /**
      * {@inheritdoc}
      */
-    public function performRequest($url, $parameters, $httpMethod = 'GET')
+    public function performRequest($url, $parameters, $httpMethod = 'GET'): ResponseInterface
     {
         $options = [
             'headers' => isset($this->options['headers']) ? $this->options['headers'] : [],
@@ -124,11 +120,14 @@ public function performRequest($url, $parameters, $httpMethod = 'GET')
     /**
      * {@inheritdoc}
      */
-    public function parseResponse($response)
+    public function parseResponse(ResponseInterface $response): array
     {
-        $responseBody = ['data' => [], 'success' => false];
+        $responseBody = [
+            'data' => [],
+            'success' => false,
+        ];
 
-        if ($response) {
+        if ((string) $response->getBody()) {
             $responseBody = json_decode($response->getBody(), true);
         }
 
@@ -136,12 +135,9 @@ public function parseResponse($response)
     }
 
     /**
-     * Push authorization middleware.
-     *
-     * @param array  $token
-     * @param string $clientId
+     * {@inheritdoc}
      */
-    public function addAuthMiddleware($token, $clientId)
+    public function addAuthMiddleware($token, string $clientId): void
     {
         $this->stack->push(Middleware::mapRequest(function (RequestInterface $request) use ($token, $clientId) {
             return (new AuthMiddleware($token, $clientId))->addAuthHeader($request);
diff --git a/lib/Imgur/HttpClient/HttpClientInterface.php b/lib/Imgur/HttpClient/HttpClientInterface.php
index 560b04f..0bf8ce0 100644
--- a/lib/Imgur/HttpClient/HttpClientInterface.php
+++ b/lib/Imgur/HttpClient/HttpClientInterface.php
@@ -2,6 +2,8 @@
 
 namespace Imgur\HttpClient;
 
+use Psr\Http\Message\ResponseInterface;
+
 /**
  * Basic client for performing HTTP requests.
  *
@@ -14,30 +16,32 @@ interface HttpClientInterface
      *
      * @param string $url        URL to which the request should point
      * @param array  $parameters Request parameters
-     *
-     * @return \Psr\Http\Message\ResponseInterface
      */
-    public function get($url, array $parameters = []);
+    public function get($url, array $parameters = []): ResponseInterface;
 
     /**
      * Perform a POST request.
      *
      * @param string $url        URL to which the request should point
      * @param array  $parameters Request parameters
-     *
-     * @return \Psr\Http\Message\ResponseInterface
      */
-    public function post($url, array $parameters = []);
+    public function post($url, array $parameters = []): ResponseInterface;
 
     /**
      * Perform a DELETE request.
      *
      * @param string $url        URL to which the request should point
      * @param array  $parameters Request parameters
+     */
+    public function delete($url, array $parameters = []): ResponseInterface;
+
+    /**
+     * Perform a PUT request.
      *
-     * @return \Psr\Http\Message\ResponseInterface
+     * @param string $url        URL to which the request should point
+     * @param array  $parameters Request parameters
      */
-    public function delete($url, array $parameters = []);
+    public function put($url, array $parameters = []): ResponseInterface;
 
     /**
      * Perform the actual request.
@@ -45,17 +49,18 @@ public function delete($url, array $parameters = []);
      * @param string $url        URL to which the request should point
      * @param array  $parameters Request parameters
      * @param string $httpMethod HTTP method to use
-     *
-     * @return \Psr\Http\Message\ResponseInterface
      */
-    public function performRequest($url, $parameters, $httpMethod = 'GET');
+    public function performRequest($url, $parameters, $httpMethod = 'GET'): ResponseInterface;
 
     /**
      * Parses the Imgur server response.
+     */
+    public function parseResponse(ResponseInterface $response): array;
+
+    /**
+     * Push authorization middleware.
      *
-     * @param object $response
-     *
-     * @return array
+     * @param array|null $token
      */
-    public function parseResponse($response);
+    public function addAuthMiddleware($token, string $clientId): void;
 }
diff --git a/lib/Imgur/Middleware/AuthMiddleware.php b/lib/Imgur/Middleware/AuthMiddleware.php
index 0ee9326..17b7ef7 100644
--- a/lib/Imgur/Middleware/AuthMiddleware.php
+++ b/lib/Imgur/Middleware/AuthMiddleware.php
@@ -6,16 +6,16 @@
 
 class AuthMiddleware
 {
+    /** @var array|null */
     private $token;
-    private $clientId;
+    private string $clientId;
 
     /**
      * Middleware that add Authorization header.
      *
-     * @param array  $token
-     * @param string $clientId
+     * @param array|null $token
      */
-    public function __construct($token, $clientId)
+    public function __construct($token, string $clientId)
     {
         $this->token = $token;
         $this->clientId = $clientId;
@@ -24,7 +24,7 @@ public function __construct($token, $clientId)
     /**
      * Add Authorization header to the request.
      */
-    public function addAuthHeader(RequestInterface $request)
+    public function addAuthHeader(RequestInterface $request): RequestInterface
     {
         if (!empty($this->token['access_token'])) {
             return $request->withHeader(
diff --git a/lib/Imgur/Middleware/ErrorMiddleware.php b/lib/Imgur/Middleware/ErrorMiddleware.php
index 0ec63f0..48716ab 100644
--- a/lib/Imgur/Middleware/ErrorMiddleware.php
+++ b/lib/Imgur/Middleware/ErrorMiddleware.php
@@ -2,6 +2,7 @@
 
 namespace Imgur\Middleware;
 
+use GuzzleHttp\Promise\PromiseInterface;
 use Imgur\Exception\ErrorException;
 use Imgur\Exception\RateLimitException;
 use Imgur\Exception\RuntimeException;
@@ -10,6 +11,7 @@
 
 class ErrorMiddleware
 {
+    /** @var callable */
     private $nextHandler;
 
     /**
@@ -20,10 +22,7 @@ public function __construct(callable $nextHandler)
         $this->nextHandler = $nextHandler;
     }
 
-    /**
-     * @return PromiseInterface
-     */
-    public function __invoke(RequestInterface $request, array $options)
+    public function __invoke(RequestInterface $request, array $options): PromiseInterface
     {
         $fn = $this->nextHandler;
 
@@ -38,7 +37,7 @@ public function __invoke(RequestInterface $request, array $options)
      *
      * @return \Closure Returns a function that accepts the next handler
      */
-    public static function error()
+    public static function error(): \Closure
     {
         return function (callable $handler) {
             return new self($handler);
@@ -48,7 +47,7 @@ public static function error()
     /**
      * Check for an error.
      */
-    public function checkError(ResponseInterface $response)
+    public function checkError(ResponseInterface $response): ?ResponseInterface
     {
         if ($response->getStatusCode() < 400) {
             return $response;
@@ -92,7 +91,7 @@ public function checkError(ResponseInterface $response)
     /**
      * Check if user hit limit.
      */
-    private function checkUserRateLimit(ResponseInterface $response)
+    private function checkUserRateLimit(ResponseInterface $response): void
     {
         $userRemaining = $response->getHeaderLine('X-RateLimit-UserRemaining');
         $userLimit = $response->getHeaderLine('X-RateLimit-UserLimit');
@@ -105,14 +104,14 @@ private function checkUserRateLimit(ResponseInterface $response)
     /**
      * Check if client hit limit.
      */
-    private function checkClientRateLimit(ResponseInterface $response)
+    private function checkClientRateLimit(ResponseInterface $response): void
     {
         $clientRemaining = $response->getHeaderLine('X-RateLimit-ClientRemaining');
         $clientLimit = $response->getHeaderLine('X-RateLimit-ClientLimit');
 
         if ('' !== $clientRemaining && $clientRemaining < 1) {
             // X-RateLimit-UserReset: Timestamp (unix epoch) for when the credits will be reset.
-            $resetTime = date('Y-m-d H:i:s', $response->getHeaderLine('X-RateLimit-UserReset'));
+            $resetTime = date('Y-m-d H:i:s', (int) $response->getHeaderLine('X-RateLimit-UserReset'));
 
             throw new RateLimitException('No application credits available. The limit is ' . $clientLimit . ' and will be reset at ' . $resetTime);
         }
@@ -121,14 +120,14 @@ private function checkClientRateLimit(ResponseInterface $response)
     /**
      * Check if client hit post limit.
      */
-    private function checkPostRateLimit(ResponseInterface $response)
+    private function checkPostRateLimit(ResponseInterface $response): void
     {
         $postRemaining = $response->getHeaderLine('X-Post-Rate-Limit-Remaining');
         $postLimit = $response->getHeaderLine('X-Post-Rate-Limit-Limit');
 
         if ('' !== $postRemaining && $postRemaining < 1) {
             // X-Post-Rate-Limit-Reset: Time in seconds until your POST ratelimit is reset
-            $resetTime = date('Y-m-d H:i:s', $response->getHeaderLine('X-Post-Rate-Limit-Reset'));
+            $resetTime = date('Y-m-d H:i:s', (int) $response->getHeaderLine('X-Post-Rate-Limit-Reset'));
 
             throw new RateLimitException('No post credits available. The limit is ' . $postLimit . ' and will be reset at ' . $resetTime);
         }
diff --git a/lib/Imgur/Pager/BasicPager.php b/lib/Imgur/Pager/BasicPager.php
index 1da6606..c81d405 100644
--- a/lib/Imgur/Pager/BasicPager.php
+++ b/lib/Imgur/Pager/BasicPager.php
@@ -11,33 +11,27 @@
  */
 class BasicPager implements PagerInterface
 {
-    private $page;
-    private $resultsPerPage;
+    private int $page;
+    private int $resultsPerPage;
 
-    public function __construct($page = 1, $resultsPerPage = 10)
+    public function __construct(int $page = 1, int $resultsPerPage = 10)
     {
         $this->setPage($page ?: 1);
         $this->setResultsPerPage($resultsPerPage ?: 10);
-
-        return $this;
     }
 
     /**
      * Get the page number to be retrieved.
-     *
-     * @return int
      */
-    public function getPage()
+    public function getPage(): int
     {
         return $this->page;
     }
 
     /**
      * Get the number of results per page.
-     *
-     * @return int
      */
-    public function getResultsPerPage()
+    public function getResultsPerPage(): int
     {
         return $this->resultsPerPage;
     }
@@ -45,11 +39,9 @@ public function getResultsPerPage()
     /**
      * Set the page number to be retrieved.
      *
-     * @param int $page
-     *
      * @return BasicPager
      */
-    public function setPage($page)
+    public function setPage(int $page): self
     {
         $this->page = $page;
 
@@ -59,11 +51,9 @@ public function setPage($page)
     /**
      * Set the number of results per page.
      *
-     * @param int $resultsPerPage
-     *
      * @return BasicPager
      */
-    public function setResultsPerPage($resultsPerPage)
+    public function setResultsPerPage(int $resultsPerPage): self
     {
         $this->resultsPerPage = $resultsPerPage;
 
diff --git a/lib/Imgur/Pager/PagerInterface.php b/lib/Imgur/Pager/PagerInterface.php
index 0b544fb..2e6f525 100644
--- a/lib/Imgur/Pager/PagerInterface.php
+++ b/lib/Imgur/Pager/PagerInterface.php
@@ -12,20 +12,20 @@ interface PagerInterface
     /**
      * Get the page number to be retrieved.
      */
-    public function getPage();
+    public function getPage(): int;
 
     /**
      * Set the page number to be retrieved.
      */
-    public function setPage($page);
+    public function setPage(int $page): self;
 
     /**
      * Get the number of results per page.
      */
-    public function getResultsPerPage();
+    public function getResultsPerPage(): int;
 
     /**
      * Set the number of results per page.
      */
-    public function setResultsPerPage($resultsPerPage);
+    public function setResultsPerPage(int $resultsPerPage): self;
 }
diff --git a/phpstan.neon b/phpstan.neon
new file mode 100644
index 0000000..9744cfb
--- /dev/null
+++ b/phpstan.neon
@@ -0,0 +1,16 @@
+parameters:
+    level: 7
+    paths:
+        - lib
+        - tests
+
+    bootstrapFiles:
+        - vendor/bin/.phpunit/phpunit-8.5-0/vendor/autoload.php
+
+    checkMissingIterableValueType: false
+
+    ignoreErrors:
+        # because the test is skipped
+        -
+            message: '#Unreachable statement#'
+            path: %currentWorkingDirectory%/tests/Api/TopicTest.php
diff --git a/tests/Api/AbstractApiTest.php b/tests/Api/AbstractApiTest.php
index ba9e86c..c9ceda4 100644
--- a/tests/Api/AbstractApiTest.php
+++ b/tests/Api/AbstractApiTest.php
@@ -9,31 +9,31 @@
 
 class AbstractApiTest extends TestCase
 {
-    public function testGet()
+    public function testGet(): void
     {
         $image = $this->getApiMock('get');
         $image->get('gallery/search/time/0', ['q' => '20minutes']);
     }
 
-    public function testDelete()
+    public function testDelete(): void
     {
         $image = $this->getApiMock('delete');
         $image->delete('image/ZOY11VC');
     }
 
-    public function testPost()
+    public function testPost(): void
     {
         $image = $this->getApiMock('post');
         $image->post('album/VOMXz', ['title' => 'yo']);
     }
 
-    public function testPut()
+    public function testPut(): void
     {
         $image = $this->getApiMock('put');
         $image->put('album/VOMXz', ['title' => 'yo']);
     }
 
-    protected function getApiMock($method)
+    protected function getApiMock(string $method): TestAbstractApi
     {
         $httpClient = $this->getMockBuilder('Imgur\HttpClient\HttpClient')
             ->disableOriginalConstructor()
diff --git a/tests/Api/AccountTest.php b/tests/Api/AccountTest.php
index 740ea56..06248d3 100644
--- a/tests/Api/AccountTest.php
+++ b/tests/Api/AccountTest.php
@@ -13,23 +13,22 @@
 
 class AccountTest extends ApiTestCase
 {
-    public function testBaseReal()
+    public function testBaseReal(): void
     {
         $this->expectException(\Imgur\Exception\ErrorException::class);
         $this->expectExceptionMessage('Authentication required');
 
-        $guzzleClient = new GuzzleClient(['base_uri' => 'https://api.imgur.com/3/']);
-        $httpClient = new HttpClient([], $guzzleClient);
+        $httpClient = new HttpClient();
         $client = new Client(null, $httpClient);
         $account = new Account($client);
 
         $account->base();
     }
 
-    public function testBaseWithResponse()
+    public function testBaseWithResponse(): void
     {
         $mock = new MockHandler([
-            new Response(200, ['Content-Type' => 'application/json'], json_encode([
+            new Response(200, ['Content-Type' => 'application/json'], (string) json_encode([
                 'data' => [
                     'id' => 703058,
                     'url' => 'j0k3rx',
@@ -45,7 +44,7 @@ public function testBaseWithResponse()
         $handler = HandlerStack::create($mock);
         $guzzleClient = new GuzzleClient(['handler' => $handler]);
 
-        $httpClient = new HttpClient([], $guzzleClient);
+        $httpClient = new HttpClient([], $guzzleClient, $handler);
         $client = new Client(null, $httpClient);
         $account = new Account($client);
 
@@ -59,7 +58,7 @@ public function testBaseWithResponse()
         $this->assertArrayHasKey('pro_expiration', $result);
     }
 
-    public function testBase()
+    public function testBase(): void
     {
         $expectedValue = [
             'data' => [
@@ -69,7 +68,7 @@ public function testBase()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('get')
             ->with('account/me')
@@ -78,7 +77,7 @@ public function testBase()
         $this->assertSame($expectedValue, $api->base());
     }
 
-    public function testDeleteAccount()
+    public function testDeleteAccount(): void
     {
         $expectedValue = [
             'data' => true,
@@ -86,7 +85,7 @@ public function testDeleteAccount()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('delete')
             ->with('account/imgur')
@@ -95,7 +94,7 @@ public function testDeleteAccount()
         $this->assertSame($expectedValue, $api->deleteAccount('imgur'));
     }
 
-    public function testGalleryFavorites()
+    public function testGalleryFavorites(): void
     {
         $expectedValue = [
             'data' => [
@@ -107,7 +106,7 @@ public function testGalleryFavorites()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('get')
             ->with('account/me/gallery_favorites/0/newest')
@@ -116,15 +115,15 @@ public function testGalleryFavorites()
         $this->assertSame($expectedValue, $api->galleryFavorites());
     }
 
-    public function testGalleryFavoritesWrongValues()
+    public function testGalleryFavoritesWrongValues(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage('is wrong. Possible values are');
 
-        $this->getApiMock()->galleryFavorites('me', 0, 'bad sort');
+        $this->getApiAccountMock()->galleryFavorites('me', 0, 'bad sort');
     }
 
-    public function testFavorites()
+    public function testFavorites(): void
     {
         $expectedValue = [
             'data' => [
@@ -136,7 +135,7 @@ public function testFavorites()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('get')
             ->with('account/me/favorites')
@@ -145,7 +144,7 @@ public function testFavorites()
         $this->assertSame($expectedValue, $api->favorites());
     }
 
-    public function testSubmissions()
+    public function testSubmissions(): void
     {
         $expectedValue = [
             'data' => [
@@ -157,7 +156,7 @@ public function testSubmissions()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('get')
             ->with('account/me/submissions/0')
@@ -166,7 +165,7 @@ public function testSubmissions()
         $this->assertSame($expectedValue, $api->submissions());
     }
 
-    public function testSettings()
+    public function testSettings(): void
     {
         $expectedValue = [
             'data' => [
@@ -178,7 +177,7 @@ public function testSettings()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('get')
             ->with('account/me/settings')
@@ -187,7 +186,7 @@ public function testSettings()
         $this->assertSame($expectedValue, $api->settings());
     }
 
-    public function testChangeAccountSettings()
+    public function testChangeAccountSettings(): void
     {
         $expectedValue = [
             'data' => true,
@@ -195,7 +194,7 @@ public function testChangeAccountSettings()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('post')
             ->with('account/me/settings')
@@ -206,7 +205,7 @@ public function testChangeAccountSettings()
         ]));
     }
 
-    public function testAccountStats()
+    public function testAccountStats(): void
     {
         $expectedValue = [
             'data' => [
@@ -218,7 +217,7 @@ public function testAccountStats()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('get')
             ->with('account/me/stats')
@@ -227,7 +226,7 @@ public function testAccountStats()
         $this->assertSame($expectedValue, $api->accountStats());
     }
 
-    public function testAccountGalleryProfile()
+    public function testAccountGalleryProfile(): void
     {
         $expectedValue = [
             'data' => [
@@ -239,7 +238,7 @@ public function testAccountGalleryProfile()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('get')
             ->with('account/me/gallery_profile')
@@ -248,7 +247,7 @@ public function testAccountGalleryProfile()
         $this->assertSame($expectedValue, $api->accountGalleryProfile());
     }
 
-    public function testVerifyUsersEmail()
+    public function testVerifyUsersEmail(): void
     {
         $expectedValue = [
             'data' => [
@@ -260,7 +259,7 @@ public function testVerifyUsersEmail()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('get')
             ->with('account/me/verifyemail')
@@ -269,7 +268,7 @@ public function testVerifyUsersEmail()
         $this->assertSame($expectedValue, $api->verifyUsersEmail());
     }
 
-    public function testSendVerificationEmail()
+    public function testSendVerificationEmail(): void
     {
         $expectedValue = [
             'data' => true,
@@ -277,7 +276,7 @@ public function testSendVerificationEmail()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('post')
             ->with('account/me/verifyemail')
@@ -286,7 +285,7 @@ public function testSendVerificationEmail()
         $this->assertSame($expectedValue, $api->sendVerificationEmail());
     }
 
-    public function testAlbums()
+    public function testAlbums(): void
     {
         $expectedValue = [
             'data' => [
@@ -298,7 +297,7 @@ public function testAlbums()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('get')
             ->with('account/me/albums/0')
@@ -307,7 +306,7 @@ public function testAlbums()
         $this->assertSame($expectedValue, $api->albums());
     }
 
-    public function testAlbum()
+    public function testAlbum(): void
     {
         $expectedValue = [
             'data' => [
@@ -319,7 +318,7 @@ public function testAlbum()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('get')
             ->with('account/me/album/Arn5NUt')
@@ -328,7 +327,7 @@ public function testAlbum()
         $this->assertSame($expectedValue, $api->album('Arn5NUt'));
     }
 
-    public function testAlbumIds()
+    public function testAlbumIds(): void
     {
         $expectedValue = [
             'data' => [
@@ -340,7 +339,7 @@ public function testAlbumIds()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('get')
             ->with('account/me/albums/ids/0')
@@ -349,7 +348,7 @@ public function testAlbumIds()
         $this->assertSame($expectedValue, $api->albumIds());
     }
 
-    public function testAlbumCount()
+    public function testAlbumCount(): void
     {
         $expectedValue = [
             'data' => [
@@ -361,7 +360,7 @@ public function testAlbumCount()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('get')
             ->with('account/me/albums/count')
@@ -370,7 +369,7 @@ public function testAlbumCount()
         $this->assertSame($expectedValue, $api->albumCount());
     }
 
-    public function testAlbumDelete()
+    public function testAlbumDelete(): void
     {
         $expectedValue = [
             'data' => true,
@@ -378,7 +377,7 @@ public function testAlbumDelete()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('delete')
             ->with('account/me/album/Arn5NUt')
@@ -387,7 +386,7 @@ public function testAlbumDelete()
         $this->assertSame($expectedValue, $api->albumDelete('Arn5NUt'));
     }
 
-    public function testComments()
+    public function testComments(): void
     {
         $expectedValue = [
             'data' => [
@@ -399,7 +398,7 @@ public function testComments()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('get')
             ->with('account/me/comments/newest/0')
@@ -408,15 +407,15 @@ public function testComments()
         $this->assertSame($expectedValue, $api->comments());
     }
 
-    public function testCommentsWrongValues()
+    public function testCommentsWrongValues(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage('is wrong. Possible values are');
 
-        $this->getApiMock()->comments('me', 0, 'bad sort');
+        $this->getApiAccountMock()->comments('me', 0, 'bad sort');
     }
 
-    public function testComment()
+    public function testComment(): void
     {
         $expectedValue = [
             'data' => [
@@ -428,7 +427,7 @@ public function testComment()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('get')
             ->with('account/me/comment/726305564')
@@ -437,7 +436,7 @@ public function testComment()
         $this->assertSame($expectedValue, $api->comment('726305564'));
     }
 
-    public function testCommentIds()
+    public function testCommentIds(): void
     {
         $expectedValue = [
             'data' => [
@@ -449,7 +448,7 @@ public function testCommentIds()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('get')
             ->with('account/me/comments/ids/newest/0')
@@ -458,15 +457,15 @@ public function testCommentIds()
         $this->assertSame($expectedValue, $api->commentIds());
     }
 
-    public function testCommentIdsWrongValues()
+    public function testCommentIdsWrongValues(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage('is wrong. Possible values are');
 
-        $this->getApiMock()->commentIds('me', 0, 'bad sort');
+        $this->getApiAccountMock()->commentIds('me', 0, 'bad sort');
     }
 
-    public function testCommentCount()
+    public function testCommentCount(): void
     {
         $expectedValue = [
             'data' => [
@@ -478,7 +477,7 @@ public function testCommentCount()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('get')
             ->with('account/me/comments/count')
@@ -487,7 +486,7 @@ public function testCommentCount()
         $this->assertSame($expectedValue, $api->commentCount());
     }
 
-    public function testCommentDelete()
+    public function testCommentDelete(): void
     {
         $expectedValue = [
             'data' => true,
@@ -495,7 +494,7 @@ public function testCommentDelete()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('delete')
             ->with('account/me/comment/726305564')
@@ -504,7 +503,7 @@ public function testCommentDelete()
         $this->assertSame($expectedValue, $api->commentDelete('726305564'));
     }
 
-    public function testImages()
+    public function testImages(): void
     {
         $expectedValue = [
             'data' => [
@@ -516,7 +515,7 @@ public function testImages()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('get')
             ->with('account/me/images/0')
@@ -525,7 +524,7 @@ public function testImages()
         $this->assertSame($expectedValue, $api->images());
     }
 
-    public function testImage()
+    public function testImage(): void
     {
         $expectedValue = [
             'data' => [
@@ -537,7 +536,7 @@ public function testImage()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('get')
             ->with('account/me/image/iCMrM1P')
@@ -546,7 +545,7 @@ public function testImage()
         $this->assertSame($expectedValue, $api->image('iCMrM1P'));
     }
 
-    public function testImageIds()
+    public function testImageIds(): void
     {
         $expectedValue = [
             'data' => [
@@ -558,7 +557,7 @@ public function testImageIds()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('get')
             ->with('account/me/images/ids/0')
@@ -567,7 +566,7 @@ public function testImageIds()
         $this->assertSame($expectedValue, $api->imageIds());
     }
 
-    public function testImageCount()
+    public function testImageCount(): void
     {
         $expectedValue = [
             'data' => [
@@ -579,7 +578,7 @@ public function testImageCount()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('get')
             ->with('account/me/images/count')
@@ -588,7 +587,7 @@ public function testImageCount()
         $this->assertSame($expectedValue, $api->imageCount());
     }
 
-    public function testImageDelete()
+    public function testImageDelete(): void
     {
         $expectedValue = [
             'data' => true,
@@ -596,7 +595,7 @@ public function testImageDelete()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('delete')
             ->with('account/me/image/iCMrM1P')
@@ -605,7 +604,7 @@ public function testImageDelete()
         $this->assertSame($expectedValue, $api->imageDelete('iCMrM1P'));
     }
 
-    public function testReplies()
+    public function testReplies(): void
     {
         $expectedValue = [
             'data' => [
@@ -617,7 +616,7 @@ public function testReplies()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAccountMock();
         $api->expects($this->once())
             ->method('get')
             ->with('account/me/notifications/replies', ['new' => 'false'])
@@ -625,9 +624,4 @@ public function testReplies()
 
         $this->assertSame($expectedValue, $api->replies());
     }
-
-    protected function getApiClass()
-    {
-        return 'Imgur\Api\Account';
-    }
 }
diff --git a/tests/Api/AlbumOrImageTest.php b/tests/Api/AlbumOrImageTest.php
index 9e08384..8a1165c 100644
--- a/tests/Api/AlbumOrImageTest.php
+++ b/tests/Api/AlbumOrImageTest.php
@@ -14,26 +14,26 @@
 
 class AlbumOrImageTest extends TestCase
 {
-    public function testWithImageId()
+    public function testWithImageId(): void
     {
         $mock = new MockHandler([
-            new Response(200, ['Content-Type' => 'application/json'], json_encode(['data' => 'ok !'])),
+            new Response(200, ['Content-Type' => 'application/json'], (string) json_encode(['data' => ['ok !']])),
         ]);
         $handler = HandlerStack::create($mock);
         $client = new GuzzleClient(['handler' => $handler]);
 
-        $httpClient = new HttpClient([], $client);
+        $httpClient = new HttpClient([], $client, $handler);
 
         $client = new Client(null, $httpClient);
         $api = new AlbumOrImage($client);
 
-        $this->assertSame('ok !', $api->find('ZOY11VC'));
+        $this->assertSame(['ok !'], $api->find('ZOY11VC'));
     }
 
-    public function testWithAlbumId()
+    public function testWithAlbumId(): void
     {
         $mock = new MockHandler([
-            new Response(404, ['Content-Type' => 'application/json'], json_encode([
+            new Response(404, ['Content-Type' => 'application/json'], (string) json_encode([
                 'data' => [
                     'error' => 'Unable to find an image with the id, 8pCqe',
                     'request' => '/3/image/8pCqe',
@@ -42,26 +42,26 @@ public function testWithAlbumId()
                 'success' => false,
                 'status' => 404,
             ])),
-            new Response(200, ['Content-Type' => 'application/json'], json_encode(['data' => 'ok !'])),
+            new Response(200, ['Content-Type' => 'application/json'], (string) json_encode(['data' => ['ok !']])),
         ]);
         $handler = HandlerStack::create($mock);
         $client = new GuzzleClient(['handler' => $handler]);
 
-        $httpClient = new HttpClient([], $client);
+        $httpClient = new HttpClient([], $client, $handler);
 
         $client = new Client(null, $httpClient);
         $api = new AlbumOrImage($client);
 
-        $this->assertSame('ok !', $api->find('8pCqe'));
+        $this->assertSame(['ok !'], $api->find('8pCqe'));
     }
 
-    public function testWithBadId()
+    public function testWithBadId(): void
     {
         $this->expectException(ErrorException::class);
         $this->expectExceptionMessage('id');
 
         $mock = new MockHandler([
-            new Response(404, ['Content-Type' => 'application/json'], json_encode([
+            new Response(404, ['Content-Type' => 'application/json'], (string) json_encode([
                 'data' => [
                     'error' => 'Unable to find an image with the id, xxxxxxx',
                     'request' => '/3/image/xxxxxxx',
@@ -70,7 +70,7 @@ public function testWithBadId()
                 'success' => false,
                 'status' => 404,
             ])),
-            new Response(404, ['Content-Type' => 'application/json'], json_encode([
+            new Response(404, ['Content-Type' => 'application/json'], (string) json_encode([
                 'data' => [
                     'error' => 'Unable to find an album with the id, xxxxxxx',
                     'request' => '/3/album/xxxxxxx',
@@ -83,7 +83,7 @@ public function testWithBadId()
         $handler = HandlerStack::create($mock);
         $client = new GuzzleClient(['handler' => $handler]);
 
-        $httpClient = new HttpClient([], $client);
+        $httpClient = new HttpClient([], $client, $handler);
 
         $client = new Client(null, $httpClient);
         $api = new AlbumOrImage($client);
@@ -91,13 +91,13 @@ public function testWithBadId()
         $api->find('xxxxxxx');
     }
 
-    public function testWithImageIdButBadResponse()
+    public function testWithImageIdButBadResponse(): void
     {
         $this->expectException(ErrorException::class);
         $this->expectExceptionMessage('oops');
 
         $mock = new MockHandler([
-            new Response(500, ['Content-Type' => 'application/json'], json_encode([
+            new Response(500, ['Content-Type' => 'application/json'], (string) json_encode([
                 'data' => [
                     'error' => 'oops !',
                     'request' => '/3/image/xxxxxxx',
@@ -110,7 +110,7 @@ public function testWithImageIdButBadResponse()
         $handler = HandlerStack::create($mock);
         $client = new GuzzleClient(['handler' => $handler]);
 
-        $httpClient = new HttpClient([], $client);
+        $httpClient = new HttpClient([], $client, $handler);
 
         $client = new Client(null, $httpClient);
         $api = new AlbumOrImage($client);
@@ -118,13 +118,13 @@ public function testWithImageIdButBadResponse()
         $api->find('ZOY11VC');
     }
 
-    public function testWithAlbumIdButBadResponse()
+    public function testWithAlbumIdButBadResponse(): void
     {
         $this->expectException(ErrorException::class);
         $this->expectExceptionMessage('oops');
 
         $mock = new MockHandler([
-            new Response(404, ['Content-Type' => 'application/json'], json_encode([
+            new Response(404, ['Content-Type' => 'application/json'], (string) json_encode([
                 'data' => [
                     'error' => 'Unable to find an image with the id, xxxxxxx',
                     'request' => '/3/image/xxxxxxx',
@@ -133,7 +133,7 @@ public function testWithAlbumIdButBadResponse()
                 'success' => false,
                 'status' => 404,
             ])),
-            new Response(500, ['Content-Type' => 'application/json'], json_encode([
+            new Response(500, ['Content-Type' => 'application/json'], (string) json_encode([
                 'data' => [
                     'error' => 'oops !',
                     'request' => '/3/image/xxxxxxx',
@@ -146,7 +146,7 @@ public function testWithAlbumIdButBadResponse()
         $handler = HandlerStack::create($mock);
         $client = new GuzzleClient(['handler' => $handler]);
 
-        $httpClient = new HttpClient([], $client);
+        $httpClient = new HttpClient([], $client, $handler);
 
         $client = new Client(null, $httpClient);
         $api = new AlbumOrImage($client);
diff --git a/tests/Api/AlbumTest.php b/tests/Api/AlbumTest.php
index 40c55f1..eb51da6 100644
--- a/tests/Api/AlbumTest.php
+++ b/tests/Api/AlbumTest.php
@@ -12,23 +12,22 @@
 
 class AlbumTest extends ApiTestCase
 {
-    public function testBaseReal()
+    public function testBaseReal(): void
     {
         $this->expectException(\Imgur\Exception\ErrorException::class);
         $this->expectExceptionMessage('Authentication required');
 
-        $guzzleClient = new GuzzleClient(['base_uri' => 'https://api.imgur.com/3/']);
-        $httpClient = new HttpClient([], $guzzleClient);
+        $httpClient = new HttpClient();
         $client = new Client(null, $httpClient);
         $album = new Album($client);
 
         $album->album('VOMXz');
     }
 
-    public function testBaseWithResponse()
+    public function testBaseWithResponse(): void
     {
         $mock = new MockHandler([
-            new Response(200, ['Content-Type' => 'application/json'], json_encode([
+            new Response(200, ['Content-Type' => 'application/json'], (string) json_encode([
                 'data' => [
                     'id' => 'VOMXz',
                     'title' => 'sample',
@@ -84,7 +83,7 @@ public function testBaseWithResponse()
         $handler = HandlerStack::create($mock);
         $guzzleClient = new GuzzleClient(['handler' => $handler]);
 
-        $httpClient = new HttpClient([], $guzzleClient);
+        $httpClient = new HttpClient([], $guzzleClient, $handler);
         $client = new Client(null, $httpClient);
         $album = new Album($client);
 
@@ -113,7 +112,7 @@ public function testBaseWithResponse()
         $this->assertArrayHasKey('images', $result);
     }
 
-    public function testAlbum()
+    public function testAlbum(): void
     {
         $expectedValue = [
             'data' => [
@@ -123,7 +122,7 @@ public function testAlbum()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAlbumMock();
         $api->expects($this->once())
             ->method('get')
             ->with('album/VOMXz')
@@ -132,7 +131,7 @@ public function testAlbum()
         $this->assertSame($expectedValue, $api->album('VOMXz'));
     }
 
-    public function testAlbumImages()
+    public function testAlbumImages(): void
     {
         $expectedValue = [
             'data' => [
@@ -142,7 +141,7 @@ public function testAlbumImages()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAlbumMock();
         $api->expects($this->once())
             ->method('get')
             ->with('album/VOMXz/images')
@@ -151,7 +150,7 @@ public function testAlbumImages()
         $this->assertSame($expectedValue, $api->albumImages('VOMXz'));
     }
 
-    public function testAlbumImage()
+    public function testAlbumImage(): void
     {
         $expectedValue = [
             'data' => [
@@ -161,7 +160,7 @@ public function testAlbumImage()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAlbumMock();
         $api->expects($this->once())
             ->method('get')
             ->with('album/VOMXz/image/POvvB')
@@ -170,7 +169,7 @@ public function testAlbumImage()
         $this->assertSame($expectedValue, $api->albumImage('VOMXz', 'POvvB'));
     }
 
-    public function testCreate()
+    public function testCreate(): void
     {
         $expectedValue = [
             'data' => true,
@@ -178,16 +177,16 @@ public function testCreate()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAlbumMock();
         $api->expects($this->once())
             ->method('post')
             ->with('album')
             ->willReturn($expectedValue);
 
-        $this->assertSame($expectedValue, $api->create('VOMXz'));
+        $this->assertSame($expectedValue, $api->create(['VOMXz']));
     }
 
-    public function testUpdate()
+    public function testUpdate(): void
     {
         $expectedValue = [
             'data' => true,
@@ -195,7 +194,7 @@ public function testUpdate()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAlbumMock();
         $api->expects($this->once())
             ->method('post')
             ->with('album/VOMXz')
@@ -206,7 +205,7 @@ public function testUpdate()
         ]));
     }
 
-    public function testDeleteAlbum()
+    public function testDeleteAlbum(): void
     {
         $expectedValue = [
             'data' => [
@@ -216,7 +215,7 @@ public function testDeleteAlbum()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAlbumMock();
         $api->expects($this->once())
             ->method('delete')
             ->with('album/VOMXz')
@@ -225,7 +224,7 @@ public function testDeleteAlbum()
         $this->assertSame($expectedValue, $api->deleteAlbum('VOMXz'));
     }
 
-    public function testFavoriteAlbum()
+    public function testFavoriteAlbum(): void
     {
         $expectedValue = [
             'data' => true,
@@ -233,7 +232,7 @@ public function testFavoriteAlbum()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAlbumMock();
         $api->expects($this->once())
             ->method('post')
             ->with('album/VOMXz/favorite')
@@ -242,7 +241,7 @@ public function testFavoriteAlbum()
         $this->assertSame($expectedValue, $api->favoriteAlbum('VOMXz'));
     }
 
-    public function testSetAlbumImages()
+    public function testSetAlbumImages(): void
     {
         $expectedValue = [
             'data' => true,
@@ -250,7 +249,7 @@ public function testSetAlbumImages()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAlbumMock();
         $api->expects($this->once())
             ->method('post')
             ->with('album/VOMXz')
@@ -259,7 +258,7 @@ public function testSetAlbumImages()
         $this->assertSame($expectedValue, $api->setAlbumImages('VOMXz', ['POvvB', 'P1vvB']));
     }
 
-    public function testAddImages()
+    public function testAddImages(): void
     {
         $expectedValue = [
             'data' => true,
@@ -267,7 +266,7 @@ public function testAddImages()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAlbumMock();
         $api->expects($this->once())
             ->method('post')
             ->with('album/VOMXz/add')
@@ -276,7 +275,7 @@ public function testAddImages()
         $this->assertSame($expectedValue, $api->addImages('VOMXz', ['POvvB', 'P1vvB']));
     }
 
-    public function testRemoveImages()
+    public function testRemoveImages(): void
     {
         $expectedValue = [
             'data' => true,
@@ -284,7 +283,7 @@ public function testRemoveImages()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiAlbumMock();
         $api->expects($this->once())
             ->method('delete')
             ->with('album/VOMXz/remove_images')
@@ -292,9 +291,4 @@ public function testRemoveImages()
 
         $this->assertSame($expectedValue, $api->removeImages('VOMXz', ['POvvB', 'P1vvB']));
     }
-
-    protected function getApiClass()
-    {
-        return 'Imgur\Api\Album';
-    }
 }
diff --git a/tests/Api/ApiTestCase.php b/tests/Api/ApiTestCase.php
index 2442a6c..894cc29 100644
--- a/tests/Api/ApiTestCase.php
+++ b/tests/Api/ApiTestCase.php
@@ -3,13 +3,97 @@
 namespace Imgur\tests\Api;
 
 use Imgur\Client;
+use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
 
 abstract class ApiTestCase extends TestCase
 {
-    abstract protected function getApiClass();
+    /**
+     * @return \Imgur\Api\Account&MockObject
+     */
+    protected function getApiAccountMock()
+    {
+        return $this->getApiMock('Imgur\Api\Account');
+    }
+
+    /**
+     * @return \Imgur\Api\Album&MockObject
+     */
+    protected function getApiAlbumMock()
+    {
+        return $this->getApiMock('Imgur\Api\Album');
+    }
+
+    /**
+     * @return \Imgur\Api\Comment&MockObject
+     */
+    protected function getApiCommentMock()
+    {
+        return $this->getApiMock('Imgur\Api\Comment');
+    }
+
+    /**
+     * @return \Imgur\Api\Conversation&MockObject
+     */
+    protected function getApiConversationMock()
+    {
+        return $this->getApiMock('Imgur\Api\Conversation');
+    }
+
+    /**
+     * @return \Imgur\Api\CustomGallery&MockObject
+     */
+    protected function getApiCustomGalleryMock()
+    {
+        return $this->getApiMock('Imgur\Api\CustomGallery');
+    }
+
+    /**
+     * @return \Imgur\Api\Gallery&MockObject
+     */
+    protected function getApiGalleryMock()
+    {
+        return $this->getApiMock('Imgur\Api\Gallery');
+    }
+
+    /**
+     * @return \Imgur\Api\Image&MockObject
+     */
+    protected function getApiImageMock()
+    {
+        return $this->getApiMock('Imgur\Api\Image');
+    }
+
+    /**
+     * @return \Imgur\Api\Memegen&MockObject
+     */
+    protected function getApiMemegenMock()
+    {
+        return $this->getApiMock('Imgur\Api\Memegen');
+    }
+
+    /**
+     * @return \Imgur\Api\Notification&MockObject
+     */
+    protected function getApiNotificationMock()
+    {
+        return $this->getApiMock('Imgur\Api\Notification');
+    }
+
+    /**
+     * @return \Imgur\Api\Topic&MockObject
+     */
+    protected function getApiTopicMock()
+    {
+        return $this->getApiMock('Imgur\Api\Topic');
+    }
 
-    protected function getApiMock()
+    /**
+     * @param class-string $class
+     *
+     * @return mixed
+     */
+    private function getApiMock($class)
     {
         $httpClient = $this->getMockBuilder('Imgur\HttpClient\HttpClient')
             ->disableOriginalConstructor()
@@ -29,8 +113,8 @@ protected function getApiMock()
 
         $client = new Client(null, $httpClient);
 
-        return $this->getMockBuilder($this->getApiClass())
-            ->setMethods(['get', 'post', 'put', 'delete'])
+        return $this->getMockBuilder($class)
+            ->onlyMethods(['get', 'post', 'put', 'delete'])
             ->setConstructorArgs([$client])
             ->getMock();
     }
diff --git a/tests/Api/CommentTest.php b/tests/Api/CommentTest.php
index f0dff54..6b701a9 100644
--- a/tests/Api/CommentTest.php
+++ b/tests/Api/CommentTest.php
@@ -12,23 +12,22 @@
 
 class CommentTest extends ApiTestCase
 {
-    public function testBaseReal()
+    public function testBaseReal(): void
     {
         $this->expectException(\Imgur\Exception\ErrorException::class);
         $this->expectExceptionMessage('Authentication required');
 
-        $guzzleClient = new GuzzleClient(['base_uri' => 'https://api.imgur.com/3/']);
-        $httpClient = new HttpClient([], $guzzleClient);
+        $httpClient = new HttpClient();
         $client = new Client(null, $httpClient);
         $comment = new Comment($client);
 
         $comment->comment('726305564');
     }
 
-    public function testBaseWithResponse()
+    public function testBaseWithResponse(): void
     {
         $mock = new MockHandler([
-            new Response(200, ['Content-Type' => 'application/json'], json_encode([
+            new Response(200, ['Content-Type' => 'application/json'], (string) json_encode([
                 'data' => [
                     'id' => 726305564,
                     'image_id' => 'XVO7F',
@@ -54,7 +53,7 @@ public function testBaseWithResponse()
         $handler = HandlerStack::create($mock);
         $guzzleClient = new GuzzleClient(['handler' => $handler]);
 
-        $httpClient = new HttpClient([], $guzzleClient);
+        $httpClient = new HttpClient([], $guzzleClient, $handler);
         $client = new Client(null, $httpClient);
         $comment = new Comment($client);
 
@@ -78,7 +77,7 @@ public function testBaseWithResponse()
         $this->assertArrayHasKey('children', $result);
     }
 
-    public function testComment()
+    public function testComment(): void
     {
         $expectedValue = [
             'data' => [
@@ -88,7 +87,7 @@ public function testComment()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiCommentMock();
         $api->expects($this->once())
             ->method('get')
             ->with('comment/726305564')
@@ -97,7 +96,7 @@ public function testComment()
         $this->assertSame($expectedValue, $api->comment('726305564'));
     }
 
-    public function testCreate()
+    public function testCreate(): void
     {
         $expectedValue = [
             'data' => true,
@@ -105,7 +104,7 @@ public function testCreate()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiCommentMock();
         $api->expects($this->once())
             ->method('post')
             ->with('comment')
@@ -114,15 +113,15 @@ public function testCreate()
         $this->assertSame($expectedValue, $api->create(['image_id' => 'ZOY11VC', 'comment' => 'I agree']));
     }
 
-    public function testCreateParamMissing()
+    public function testCreateParamMissing(): void
     {
         $this->expectException(\Imgur\Exception\MissingArgumentException::class);
         $this->expectExceptionMessage('parameters is missing');
 
-        $this->getApiMock()->create('726305564');
+        $this->getApiCommentMock()->create(['726305564']);
     }
 
-    public function testDeleteComment()
+    public function testDeleteComment(): void
     {
         $expectedValue = [
             'data' => true,
@@ -130,7 +129,7 @@ public function testDeleteComment()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiCommentMock();
         $api->expects($this->once())
             ->method('delete')
             ->with('comment/726305564')
@@ -139,7 +138,7 @@ public function testDeleteComment()
         $this->assertSame($expectedValue, $api->deleteComment('726305564'));
     }
 
-    public function testReplies()
+    public function testReplies(): void
     {
         $expectedValue = [
             'data' => [
@@ -149,7 +148,7 @@ public function testReplies()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiCommentMock();
         $api->expects($this->once())
             ->method('get')
             ->with('comment/726305564/replied')
@@ -158,7 +157,7 @@ public function testReplies()
         $this->assertSame($expectedValue, $api->replies('726305564'));
     }
 
-    public function testCreateReply()
+    public function testCreateReply(): void
     {
         $expectedValue = [
             'data' => true,
@@ -166,7 +165,7 @@ public function testCreateReply()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiCommentMock();
         $api->expects($this->once())
             ->method('post')
             ->with('comment/726305565')
@@ -175,15 +174,15 @@ public function testCreateReply()
         $this->assertSame($expectedValue, $api->createReply('726305565', ['image_id' => 'ZOY11VC', 'comment' => 'I agree']));
     }
 
-    public function testCreateReplyParamMissing()
+    public function testCreateReplyParamMissing(): void
     {
         $this->expectException(\Imgur\Exception\MissingArgumentException::class);
         $this->expectExceptionMessage('parameters is missing');
 
-        $this->getApiMock()->createReply('726305564', []);
+        $this->getApiCommentMock()->createReply('726305564', []);
     }
 
-    public function testVote()
+    public function testVote(): void
     {
         $expectedValue = [
             'data' => true,
@@ -191,7 +190,7 @@ public function testVote()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiCommentMock();
         $api->expects($this->once())
             ->method('post')
             ->with('comment/726305564/vote/up')
@@ -200,15 +199,15 @@ public function testVote()
         $this->assertSame($expectedValue, $api->vote('726305564', 'up'));
     }
 
-    public function testVoteWrongVoteValue()
+    public function testVoteWrongVoteValue(): void
     {
         $this->expectException(\Imgur\Exception\InvalidArgumentException::class);
         $this->expectExceptionMessage('is wrong. Possible values are');
 
-        $this->getApiMock()->vote('726305564', 'bad vote');
+        $this->getApiCommentMock()->vote('726305564', 'bad vote');
     }
 
-    public function testReport()
+    public function testReport(): void
     {
         $expectedValue = [
             'data' => true,
@@ -216,7 +215,7 @@ public function testReport()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiCommentMock();
         $api->expects($this->once())
             ->method('post')
             ->with('comment/726305564/report')
@@ -224,9 +223,4 @@ public function testReport()
 
         $this->assertSame($expectedValue, $api->report('726305564'));
     }
-
-    protected function getApiClass()
-    {
-        return 'Imgur\Api\Comment';
-    }
 }
diff --git a/tests/Api/ConversationTest.php b/tests/Api/ConversationTest.php
index 0856d20..63c29e1 100644
--- a/tests/Api/ConversationTest.php
+++ b/tests/Api/ConversationTest.php
@@ -12,23 +12,22 @@
 
 class ConversationTest extends ApiTestCase
 {
-    public function testBaseReal()
+    public function testBaseReal(): void
     {
         $this->expectException(\Imgur\Exception\ErrorException::class);
         $this->expectExceptionMessage('Authentication required');
 
-        $guzzleClient = new GuzzleClient(['base_uri' => 'https://api.imgur.com/3/']);
-        $httpClient = new HttpClient([], $guzzleClient);
+        $httpClient = new HttpClient();
         $client = new Client(null, $httpClient);
         $conversation = new Conversation($client);
 
         $conversation->conversations();
     }
 
-    public function testBaseWithResponse()
+    public function testBaseWithResponse(): void
     {
         $mock = new MockHandler([
-            new Response(200, ['Content-Type' => 'application/json'], json_encode([
+            new Response(200, ['Content-Type' => 'application/json'], (string) json_encode([
                 'data' => [
                     [
                         'id' => 11247233,
@@ -46,7 +45,7 @@ public function testBaseWithResponse()
         $handler = HandlerStack::create($mock);
         $guzzleClient = new GuzzleClient(['handler' => $handler]);
 
-        $httpClient = new HttpClient([], $guzzleClient);
+        $httpClient = new HttpClient([], $guzzleClient, $handler);
         $client = new Client(null, $httpClient);
         $conversation = new Conversation($client);
 
@@ -60,7 +59,7 @@ public function testBaseWithResponse()
         $this->assertArrayhasKey('datetime', $result[0]);
     }
 
-    public function testConversations()
+    public function testConversations(): void
     {
         $expectedValue = [
             'data' => [
@@ -72,7 +71,7 @@ public function testConversations()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiConversationMock();
         $api->expects($this->once())
             ->method('get')
             ->with('conversations')
@@ -81,7 +80,7 @@ public function testConversations()
         $this->assertSame($expectedValue, $api->conversations());
     }
 
-    public function testConversation()
+    public function testConversation(): void
     {
         $expectedValue = [
             'data' => [
@@ -91,7 +90,7 @@ public function testConversation()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiConversationMock();
         $api->expects($this->once())
             ->method('get')
             ->with('conversations/11247233')
@@ -100,7 +99,7 @@ public function testConversation()
         $this->assertSame($expectedValue, $api->conversation('11247233'));
     }
 
-    public function testMessageCreate()
+    public function testMessageCreate(): void
     {
         $expectedValue = [
             'data' => true,
@@ -108,7 +107,7 @@ public function testMessageCreate()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiConversationMock();
         $api->expects($this->once())
             ->method('post')
             ->with('conversations/imgur')
@@ -117,15 +116,15 @@ public function testMessageCreate()
         $this->assertSame($expectedValue, $api->messageCreate(['recipient' => 'imgur', 'body' => 'YO !']));
     }
 
-    public function testMessageCreateParamMissing()
+    public function testMessageCreateParamMissing(): void
     {
         $this->expectException(\Imgur\Exception\MissingArgumentException::class);
         $this->expectExceptionMessage('parameters is missing');
 
-        $this->getApiMock()->messageCreate([]);
+        $this->getApiConversationMock()->messageCreate([]);
     }
 
-    public function testConversationDelete()
+    public function testConversationDelete(): void
     {
         $expectedValue = [
             'data' => true,
@@ -133,7 +132,7 @@ public function testConversationDelete()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiConversationMock();
         $api->expects($this->once())
             ->method('delete')
             ->with('conversations/11247233')
@@ -142,7 +141,7 @@ public function testConversationDelete()
         $this->assertSame($expectedValue, $api->conversationDelete('11247233'));
     }
 
-    public function testReportSender()
+    public function testReportSender(): void
     {
         $expectedValue = [
             'data' => true,
@@ -150,7 +149,7 @@ public function testReportSender()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiConversationMock();
         $api->expects($this->once())
             ->method('post')
             ->with('conversations/report/imgur')
@@ -159,7 +158,7 @@ public function testReportSender()
         $this->assertSame($expectedValue, $api->reportSender('imgur'));
     }
 
-    public function testBlockSender()
+    public function testBlockSender(): void
     {
         $expectedValue = [
             'data' => true,
@@ -167,7 +166,7 @@ public function testBlockSender()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiConversationMock();
         $api->expects($this->once())
             ->method('post')
             ->with('conversations/block/imgur')
@@ -175,9 +174,4 @@ public function testBlockSender()
 
         $this->assertSame($expectedValue, $api->blockSender('imgur'));
     }
-
-    protected function getApiClass()
-    {
-        return 'Imgur\Api\Conversation';
-    }
 }
diff --git a/tests/Api/CustomGalleryTest.php b/tests/Api/CustomGalleryTest.php
index 1e8ce5c..2b2b088 100644
--- a/tests/Api/CustomGalleryTest.php
+++ b/tests/Api/CustomGalleryTest.php
@@ -13,23 +13,22 @@
 
 class CustomGalleryTest extends ApiTestCase
 {
-    public function testBaseReal()
+    public function testBaseReal(): void
     {
         $this->expectException(\Imgur\Exception\ErrorException::class);
         $this->expectExceptionMessage('Authentication required');
 
-        $guzzleClient = new GuzzleClient(['base_uri' => 'https://api.imgur.com/3/']);
-        $httpClient = new HttpClient([], $guzzleClient);
+        $httpClient = new HttpClient();
         $client = new Client(null, $httpClient);
         $customGallery = new CustomGallery($client);
 
         $customGallery->customGallery();
     }
 
-    public function testBaseWithResponse()
+    public function testBaseWithResponse(): void
     {
         $mock = new MockHandler([
-            new Response(200, ['Content-Type' => 'application/json'], json_encode([
+            new Response(200, ['Content-Type' => 'application/json'], (string) json_encode([
                 'data' => [
                     'link' => 'http://imgur.com/custom',
                     'tags' => [
@@ -77,7 +76,7 @@ public function testBaseWithResponse()
         $handler = HandlerStack::create($mock);
         $guzzleClient = new GuzzleClient(['handler' => $handler]);
 
-        $httpClient = new HttpClient([], $guzzleClient);
+        $httpClient = new HttpClient([], $guzzleClient, $handler);
         $client = new Client(null, $httpClient);
         $customGallery = new CustomGallery($client);
 
@@ -90,7 +89,7 @@ public function testBaseWithResponse()
         $this->assertArrayHasKey('items', $result);
     }
 
-    public function testCustomGallery()
+    public function testCustomGallery(): void
     {
         $expectedValue = [
             'data' => [
@@ -100,7 +99,7 @@ public function testCustomGallery()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiCustomGalleryMock();
         $api->expects($this->once())
             ->method('get')
             ->with('g/custom/viral/week/0')
@@ -109,23 +108,23 @@ public function testCustomGallery()
         $this->assertSame($expectedValue, $api->customGallery());
     }
 
-    public function testCustomGalleryWrongSortValue()
+    public function testCustomGalleryWrongSortValue(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage('is wrong. Possible values are');
 
-        $this->getApiMock()->customGallery('bad sort');
+        $this->getApiCustomGalleryMock()->customGallery('bad sort');
     }
 
-    public function testCustomGalleryWrongWindowValue()
+    public function testCustomGalleryWrongWindowValue(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage('is wrong. Possible values are');
 
-        $this->getApiMock()->customGallery('viral', 0, 'bad window');
+        $this->getApiCustomGalleryMock()->customGallery('viral', 0, 'bad window');
     }
 
-    public function testFiltered()
+    public function testFiltered(): void
     {
         $expectedValue = [
             'data' => [
@@ -135,7 +134,7 @@ public function testFiltered()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiCustomGalleryMock();
         $api->expects($this->once())
             ->method('get')
             ->with('g/filtered/viral/week/0')
@@ -144,23 +143,23 @@ public function testFiltered()
         $this->assertSame($expectedValue, $api->filtered());
     }
 
-    public function testFilteredWrongSortValue()
+    public function testFilteredWrongSortValue(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage('is wrong. Possible values are');
 
-        $this->getApiMock()->filtered('bad sort');
+        $this->getApiCustomGalleryMock()->filtered('bad sort');
     }
 
-    public function testFilteredWrongWindowValue()
+    public function testFilteredWrongWindowValue(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage('is wrong. Possible values are');
 
-        $this->getApiMock()->filtered('viral', 0, 'bad window');
+        $this->getApiCustomGalleryMock()->filtered('viral', 0, 'bad window');
     }
 
-    public function testImage()
+    public function testImage(): void
     {
         $expectedValue = [
             'data' => [
@@ -170,7 +169,7 @@ public function testImage()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiCustomGalleryMock();
         $api->expects($this->once())
             ->method('get')
             ->with('g/custom/ccWiaRJ')
@@ -179,7 +178,7 @@ public function testImage()
         $this->assertSame($expectedValue, $api->image('ccWiaRJ'));
     }
 
-    public function testAddTags()
+    public function testAddTags(): void
     {
         $expectedValue = [
             'data' => true,
@@ -187,7 +186,7 @@ public function testAddTags()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiCustomGalleryMock();
         $api->expects($this->once())
             ->method('put')
             ->with('g/add_tags', ['tags' => 'cats,funny'])
@@ -196,7 +195,7 @@ public function testAddTags()
         $this->assertSame($expectedValue, $api->addTags(['cats', 'funny']));
     }
 
-    public function testRemoveTags()
+    public function testRemoveTags(): void
     {
         $expectedValue = [
             'data' => true,
@@ -204,7 +203,7 @@ public function testRemoveTags()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiCustomGalleryMock();
         $api->expects($this->once())
             ->method('delete')
             ->with('g/remove_tags', ['tags' => 'cats,funny'])
@@ -213,7 +212,7 @@ public function testRemoveTags()
         $this->assertSame($expectedValue, $api->removeTags(['cats', 'funny']));
     }
 
-    public function testBlockTag()
+    public function testBlockTag(): void
     {
         $expectedValue = [
             'data' => true,
@@ -221,7 +220,7 @@ public function testBlockTag()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiCustomGalleryMock();
         $api->expects($this->once())
             ->method('post')
             ->with('g/block_tag', ['tag' => 'funny'])
@@ -230,7 +229,7 @@ public function testBlockTag()
         $this->assertSame($expectedValue, $api->blockTag('funny'));
     }
 
-    public function testUnBlockTag()
+    public function testUnBlockTag(): void
     {
         $expectedValue = [
             'data' => true,
@@ -238,7 +237,7 @@ public function testUnBlockTag()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiCustomGalleryMock();
         $api->expects($this->once())
             ->method('post')
             ->with('g/unblock_tag', ['tag' => 'funny'])
@@ -246,9 +245,4 @@ public function testUnBlockTag()
 
         $this->assertSame($expectedValue, $api->unBlockTag('funny'));
     }
-
-    protected function getApiClass()
-    {
-        return 'Imgur\Api\CustomGallery';
-    }
 }
diff --git a/tests/Api/GalleryTest.php b/tests/Api/GalleryTest.php
index 14d5196..4220c09 100644
--- a/tests/Api/GalleryTest.php
+++ b/tests/Api/GalleryTest.php
@@ -13,23 +13,22 @@
 
 class GalleryTest extends ApiTestCase
 {
-    public function testBaseReal()
+    public function testBaseReal(): void
     {
         $this->expectException(\Imgur\Exception\ErrorException::class);
         $this->expectExceptionMessage('Authentication required');
 
-        $guzzleClient = new GuzzleClient(['base_uri' => 'https://api.imgur.com/3/']);
-        $httpClient = new HttpClient([], $guzzleClient);
+        $httpClient = new HttpClient();
         $client = new Client(null, $httpClient);
         $gallery = new Gallery($client);
 
         $gallery->gallery();
     }
 
-    public function testBaseWithResponse()
+    public function testBaseWithResponse(): void
     {
         $mock = new MockHandler([
-            new Response(200, ['Content-Type' => 'application/json'], json_encode([
+            new Response(200, ['Content-Type' => 'application/json'], (string) json_encode([
                 'data' => [
                     [
                         'id' => 'y1Od4',
@@ -69,7 +68,7 @@ public function testBaseWithResponse()
         $handler = HandlerStack::create($mock);
         $guzzleClient = new GuzzleClient(['handler' => $handler]);
 
-        $httpClient = new HttpClient([], $guzzleClient);
+        $httpClient = new HttpClient([], $guzzleClient, $handler);
         $client = new Client(null, $httpClient);
         $gallery = new Gallery($client);
 
@@ -105,7 +104,7 @@ public function testBaseWithResponse()
         $this->assertArrayHasKey('is_ad', $result[0]);
     }
 
-    public function testGallery()
+    public function testGallery(): void
     {
         $expectedValue = [
             'data' => [
@@ -117,7 +116,7 @@ public function testGallery()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiGalleryMock();
         $api->expects($this->once())
             ->method('get')
             ->with('gallery/hot/viral/day/0', ['showViral' => 'true'])
@@ -126,31 +125,31 @@ public function testGallery()
         $this->assertSame($expectedValue, $api->gallery());
     }
 
-    public function testGalleryWrongSortValue()
+    public function testGalleryWrongSortValue(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage('is wrong. Possible values are');
 
-        $this->getApiMock()->gallery('hot', 'bad sort');
+        $this->getApiGalleryMock()->gallery('hot', 'bad sort');
     }
 
-    public function testGalleryWrongSectionValue()
+    public function testGalleryWrongSectionValue(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage('is wrong. Possible values are');
 
-        $this->getApiMock()->gallery('bad section');
+        $this->getApiGalleryMock()->gallery('bad section');
     }
 
-    public function testGalleryWrongWindowValue()
+    public function testGalleryWrongWindowValue(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage('is wrong. Possible values are');
 
-        $this->getApiMock()->gallery('hot', 'viral', 0, 'bad window');
+        $this->getApiGalleryMock()->gallery('hot', 'viral', 0, 'bad window');
     }
 
-    public function testMemesSubgallery()
+    public function testMemesSubgallery(): void
     {
         $expectedValue = [
             'data' => [
@@ -162,7 +161,7 @@ public function testMemesSubgallery()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiGalleryMock();
         $api->expects($this->once())
             ->method('get')
             ->with('g/memes/viral/day/0')
@@ -171,23 +170,23 @@ public function testMemesSubgallery()
         $this->assertSame($expectedValue, $api->memesSubgallery());
     }
 
-    public function testMemesSubgalleryWrongSortValue()
+    public function testMemesSubgalleryWrongSortValue(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage('is wrong. Possible values are');
 
-        $this->getApiMock()->memesSubgallery('bad sort');
+        $this->getApiGalleryMock()->memesSubgallery('bad sort');
     }
 
-    public function testMemesSubgalleryWrongWindowValue()
+    public function testMemesSubgalleryWrongWindowValue(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage('is wrong. Possible values are');
 
-        $this->getApiMock()->memesSubgallery('viral', 0, 'bad window');
+        $this->getApiGalleryMock()->memesSubgallery('viral', 0, 'bad window');
     }
 
-    public function testMemeSubgalleryImage()
+    public function testMemeSubgalleryImage(): void
     {
         $expectedValue = [
             'data' => [
@@ -197,7 +196,7 @@ public function testMemeSubgalleryImage()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiGalleryMock();
         $api->expects($this->once())
             ->method('get')
             ->with('g/memes/MPx6ZXr')
@@ -206,7 +205,7 @@ public function testMemeSubgalleryImage()
         $this->assertSame($expectedValue, $api->memeSubgalleryImage('MPx6ZXr'));
     }
 
-    public function testSubredditGalleries()
+    public function testSubredditGalleries(): void
     {
         $expectedValue = [
             'data' => [
@@ -218,7 +217,7 @@ public function testSubredditGalleries()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiGalleryMock();
         $api->expects($this->once())
             ->method('get')
             ->with('gallery/r/pics/time/day/0')
@@ -227,23 +226,23 @@ public function testSubredditGalleries()
         $this->assertSame($expectedValue, $api->subredditGalleries('pics'));
     }
 
-    public function testSubredditGalleriesWrongSortValue()
+    public function testSubredditGalleriesWrongSortValue(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage('is wrong. Possible values are');
 
-        $this->getApiMock()->subredditGalleries('pics', 'bad sort');
+        $this->getApiGalleryMock()->subredditGalleries('pics', 'bad sort');
     }
 
-    public function testSubredditGalleriesWrongWindowValue()
+    public function testSubredditGalleriesWrongWindowValue(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage('is wrong. Possible values are');
 
-        $this->getApiMock()->subredditGalleries('pics', 'time', 0, 'bad window');
+        $this->getApiGalleryMock()->subredditGalleries('pics', 'time', 0, 'bad window');
     }
 
-    public function testSubredditImage()
+    public function testSubredditImage(): void
     {
         $expectedValue = [
             'data' => [
@@ -255,7 +254,7 @@ public function testSubredditImage()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiGalleryMock();
         $api->expects($this->once())
             ->method('get')
             ->with('gallery/r/pics/yB1PpjL')
@@ -264,7 +263,7 @@ public function testSubredditImage()
         $this->assertSame($expectedValue, $api->subredditImage('pics', 'yB1PpjL'));
     }
 
-    public function testGalleryTag()
+    public function testGalleryTag(): void
     {
         $expectedValue = [
             'data' => [
@@ -274,7 +273,7 @@ public function testGalleryTag()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiGalleryMock();
         $api->expects($this->once())
             ->method('get')
             ->with('gallery/t/funny/viral/week/0')
@@ -283,23 +282,23 @@ public function testGalleryTag()
         $this->assertSame($expectedValue, $api->galleryTag('funny'));
     }
 
-    public function testGalleryTagWrongSortValue()
+    public function testGalleryTagWrongSortValue(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage('is wrong. Possible values are');
 
-        $this->getApiMock()->galleryTag('funny', 'bad sort');
+        $this->getApiGalleryMock()->galleryTag('funny', 'bad sort');
     }
 
-    public function testGalleryTagWrongWindowValue()
+    public function testGalleryTagWrongWindowValue(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage('is wrong. Possible values are');
 
-        $this->getApiMock()->galleryTag('funny', 'time', 0, 'bad window');
+        $this->getApiGalleryMock()->galleryTag('funny', 'time', 0, 'bad window');
     }
 
-    public function testGalleryTagImage()
+    public function testGalleryTagImage(): void
     {
         $expectedValue = [
             'data' => [
@@ -309,7 +308,7 @@ public function testGalleryTagImage()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiGalleryMock();
         $api->expects($this->once())
             ->method('get')
             ->with('gallery/t/funny/yB1PpjL')
@@ -318,7 +317,7 @@ public function testGalleryTagImage()
         $this->assertSame($expectedValue, $api->galleryTagImage('funny', 'yB1PpjL'));
     }
 
-    public function testGalleryItemTags()
+    public function testGalleryItemTags(): void
     {
         $expectedValue = [
             'data' => [
@@ -328,7 +327,7 @@ public function testGalleryItemTags()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiGalleryMock();
         $api->expects($this->once())
             ->method('get')
             ->with('gallery/y1Od4/tags')
@@ -337,7 +336,7 @@ public function testGalleryItemTags()
         $this->assertSame($expectedValue, $api->galleryItemTags('y1Od4'));
     }
 
-    public function testGalleryVoteTag()
+    public function testGalleryVoteTag(): void
     {
         $expectedValue = [
             'data' => true,
@@ -345,7 +344,7 @@ public function testGalleryVoteTag()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiGalleryMock();
         $api->expects($this->once())
             ->method('post')
             ->with('gallery/y1Od4/vote/tag/funny/up')
@@ -354,15 +353,15 @@ public function testGalleryVoteTag()
         $this->assertSame($expectedValue, $api->galleryVoteTag('y1Od4', 'funny', 'up'));
     }
 
-    public function testGalleryVoteTagWrongVoteValue()
+    public function testGalleryVoteTagWrongVoteValue(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage('is wrong. Possible values are');
 
-        $this->getApiMock()->galleryVoteTag('y1Od4', 'funny', 'bad vote');
+        $this->getApiGalleryMock()->galleryVoteTag('y1Od4', 'funny', 'bad vote');
     }
 
-    public function testSearch()
+    public function testSearch(): void
     {
         $expectedValue = [
             'data' => [
@@ -374,7 +373,7 @@ public function testSearch()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiGalleryMock();
         $api->expects($this->once())
             ->method('get')
             ->with('gallery/search/time/0', ['q' => '20minutes'])
@@ -383,15 +382,15 @@ public function testSearch()
         $this->assertSame($expectedValue, $api->search('20minutes'));
     }
 
-    public function testSearchWrongValues()
+    public function testSearchWrongValues(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage('is wrong. Possible values are');
 
-        $this->getApiMock()->search('pics', 'bad sort');
+        $this->getApiGalleryMock()->search('pics', 'bad sort');
     }
 
-    public function testRandomGalleryImages()
+    public function testRandomGalleryImages(): void
     {
         $expectedValue = [
             'data' => [
@@ -403,7 +402,7 @@ public function testRandomGalleryImages()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiGalleryMock();
         $api->expects($this->once())
             ->method('get')
             ->with('gallery/random/random/0')
@@ -412,7 +411,7 @@ public function testRandomGalleryImages()
         $this->assertSame($expectedValue, $api->randomGalleryImages());
     }
 
-    public function testSubmitToGallery()
+    public function testSubmitToGallery(): void
     {
         $expectedValue = [
             'data' => true,
@@ -420,7 +419,7 @@ public function testSubmitToGallery()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiGalleryMock();
         $api->expects($this->once())
             ->method('post')
             ->with('gallery/y1Od4')
@@ -429,15 +428,15 @@ public function testSubmitToGallery()
         $this->assertSame($expectedValue, $api->submitToGallery('y1Od4', ['title' => 'yo']));
     }
 
-    public function testSubmitToGalleryParamMissing()
+    public function testSubmitToGalleryParamMissing(): void
     {
         $this->expectException(\Imgur\Exception\MissingArgumentException::class);
         $this->expectExceptionMessage('parameters is missing');
 
-        $this->getApiMock()->submitToGallery('y1Od4', []);
+        $this->getApiGalleryMock()->submitToGallery('y1Od4', []);
     }
 
-    public function testRemoveFromGallery()
+    public function testRemoveFromGallery(): void
     {
         $expectedValue = [
             'data' => true,
@@ -445,7 +444,7 @@ public function testRemoveFromGallery()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiGalleryMock();
         $api->expects($this->once())
             ->method('delete')
             ->with('gallery/ccWiaRJ')
@@ -454,7 +453,7 @@ public function testRemoveFromGallery()
         $this->assertSame($expectedValue, $api->removeFromGallery('ccWiaRJ'));
     }
 
-    public function testAlbum()
+    public function testAlbum(): void
     {
         $expectedValue = [
             'data' => [
@@ -464,7 +463,7 @@ public function testAlbum()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiGalleryMock();
         $api->expects($this->once())
             ->method('get')
             ->with('gallery/album/VOMXz')
@@ -473,7 +472,7 @@ public function testAlbum()
         $this->assertSame($expectedValue, $api->album('VOMXz'));
     }
 
-    public function testImage()
+    public function testImage(): void
     {
         $expectedValue = [
             'data' => [
@@ -483,7 +482,7 @@ public function testImage()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiGalleryMock();
         $api->expects($this->once())
             ->method('get')
             ->with('gallery/image/ccWiaRJ')
@@ -492,7 +491,7 @@ public function testImage()
         $this->assertSame($expectedValue, $api->image('ccWiaRJ'));
     }
 
-    public function testReport()
+    public function testReport(): void
     {
         $expectedValue = [
             'data' => true,
@@ -500,7 +499,7 @@ public function testReport()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiGalleryMock();
         $api->expects($this->once())
             ->method('post')
             ->with('gallery/VOMXz/report')
@@ -509,7 +508,7 @@ public function testReport()
         $this->assertSame($expectedValue, $api->report('VOMXz'));
     }
 
-    public function testVotes()
+    public function testVotes(): void
     {
         $expectedValue = [
             'data' => [
@@ -519,7 +518,7 @@ public function testVotes()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiGalleryMock();
         $api->expects($this->once())
             ->method('get')
             ->with('gallery/VOMXz/votes')
@@ -528,7 +527,7 @@ public function testVotes()
         $this->assertSame($expectedValue, $api->votes('VOMXz'));
     }
 
-    public function testVote()
+    public function testVote(): void
     {
         $expectedValue = [
             'data' => true,
@@ -536,7 +535,7 @@ public function testVote()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiGalleryMock();
         $api->expects($this->once())
             ->method('post')
             ->with('gallery/VOMXz/vote/up')
@@ -545,15 +544,15 @@ public function testVote()
         $this->assertSame($expectedValue, $api->vote('VOMXz', 'up'));
     }
 
-    public function testVoteWrongVoteValue()
+    public function testVoteWrongVoteValue(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage('is wrong. Possible values are');
 
-        $this->getApiMock()->vote('VOMXz', 'bad vote');
+        $this->getApiGalleryMock()->vote('VOMXz', 'bad vote');
     }
 
-    public function testComments()
+    public function testComments(): void
     {
         $expectedValue = [
             'data' => [
@@ -565,7 +564,7 @@ public function testComments()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiGalleryMock();
         $api->expects($this->once())
             ->method('get')
             ->with('gallery/VOMXz/comments/best')
@@ -574,15 +573,15 @@ public function testComments()
         $this->assertSame($expectedValue, $api->comments('VOMXz'));
     }
 
-    public function testCommentsWrongValues()
+    public function testCommentsWrongValues(): void
     {
         $this->expectException(InvalidArgumentException::class);
         $this->expectExceptionMessage('is wrong. Possible values are');
 
-        $this->getApiMock()->comments('VOMXz', 'bad sort');
+        $this->getApiGalleryMock()->comments('VOMXz', 'bad sort');
     }
 
-    public function testComment()
+    public function testComment(): void
     {
         $expectedValue = [
             'data' => [
@@ -592,7 +591,7 @@ public function testComment()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiGalleryMock();
         $api->expects($this->once())
             ->method('get')
             ->with('gallery/VOMXz/comment/1234')
@@ -601,7 +600,7 @@ public function testComment()
         $this->assertSame($expectedValue, $api->comment('VOMXz', '1234'));
     }
 
-    public function testCreateComment()
+    public function testCreateComment(): void
     {
         $expectedValue = [
             'data' => true,
@@ -609,7 +608,7 @@ public function testCreateComment()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiGalleryMock();
         $api->expects($this->once())
             ->method('post')
             ->with('gallery/VOMXz/comment')
@@ -618,15 +617,15 @@ public function testCreateComment()
         $this->assertSame($expectedValue, $api->createComment('VOMXz', ['comment' => 'yo']));
     }
 
-    public function testCreateCommentParamMissing()
+    public function testCreateCommentParamMissing(): void
     {
         $this->expectException(\Imgur\Exception\MissingArgumentException::class);
         $this->expectExceptionMessage('parameters is missing');
 
-        $this->getApiMock()->createComment('y1Od4', []);
+        $this->getApiGalleryMock()->createComment('y1Od4', []);
     }
 
-    public function testCreateReply()
+    public function testCreateReply(): void
     {
         $expectedValue = [
             'data' => true,
@@ -634,7 +633,7 @@ public function testCreateReply()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiGalleryMock();
         $api->expects($this->once())
             ->method('post')
             ->with('gallery/VOMXz/comment/123')
@@ -643,15 +642,15 @@ public function testCreateReply()
         $this->assertSame($expectedValue, $api->createReply('VOMXz', '123', ['comment' => 'yo']));
     }
 
-    public function testCreateReplyParamMissing()
+    public function testCreateReplyParamMissing(): void
     {
         $this->expectException(\Imgur\Exception\MissingArgumentException::class);
         $this->expectExceptionMessage('parameters is missing');
 
-        $this->getApiMock()->createReply('y1Od4', '123', []);
+        $this->getApiGalleryMock()->createReply('y1Od4', '123', []);
     }
 
-    public function testCommentIds()
+    public function testCommentIds(): void
     {
         $expectedValue = [
             'data' => [
@@ -663,7 +662,7 @@ public function testCommentIds()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiGalleryMock();
         $api->expects($this->once())
             ->method('get')
             ->with('gallery/VOMXz/comments/ids')
@@ -672,7 +671,7 @@ public function testCommentIds()
         $this->assertSame($expectedValue, $api->commentIds('VOMXz'));
     }
 
-    public function testCommentCount()
+    public function testCommentCount(): void
     {
         $expectedValue = [
             'data' => 21,
@@ -680,7 +679,7 @@ public function testCommentCount()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiGalleryMock();
         $api->expects($this->once())
             ->method('get')
             ->with('gallery/VOMXz/comments/count')
@@ -688,9 +687,4 @@ public function testCommentCount()
 
         $this->assertSame($expectedValue, $api->commentCount('VOMXz'));
     }
-
-    protected function getApiClass()
-    {
-        return 'Imgur\Api\Gallery';
-    }
 }
diff --git a/tests/Api/ImageTest.php b/tests/Api/ImageTest.php
index 6f6cb16..844c624 100644
--- a/tests/Api/ImageTest.php
+++ b/tests/Api/ImageTest.php
@@ -12,23 +12,22 @@
 
 class ImageTest extends ApiTestCase
 {
-    public function testBaseReal()
+    public function testBaseReal(): void
     {
         $this->expectException(\Imgur\Exception\ErrorException::class);
         $this->expectExceptionMessage('Authentication required');
 
-        $guzzleClient = new GuzzleClient(['base_uri' => 'https://api.imgur.com/3/']);
-        $httpClient = new HttpClient([], $guzzleClient);
+        $httpClient = new HttpClient();
         $client = new Client(null, $httpClient);
         $image = new Image($client);
 
         $image->image('ZOY11VC');
     }
 
-    public function testBaseWithResponse()
+    public function testBaseWithResponse(): void
     {
         $mock = new MockHandler([
-            new Response(200, ['Content-Type' => 'application/json'], json_encode([
+            new Response(200, ['Content-Type' => 'application/json'], (string) json_encode([
                 'data' => [
                     'id' => 'ZOY11VC',
                     'title' => null,
@@ -60,7 +59,7 @@ public function testBaseWithResponse()
         $handler = HandlerStack::create($mock);
         $guzzleClient = new GuzzleClient(['handler' => $handler]);
 
-        $httpClient = new HttpClient([], $guzzleClient);
+        $httpClient = new HttpClient([], $guzzleClient, $handler);
         $client = new Client(null, $httpClient);
         $image = new Image($client);
 
@@ -90,7 +89,7 @@ public function testBaseWithResponse()
         $this->assertArrayHasKey('link', $result);
     }
 
-    public function testImage()
+    public function testImage(): void
     {
         $expectedValue = [
             'data' => [
@@ -100,7 +99,7 @@ public function testImage()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiImageMock();
         $api->expects($this->once())
             ->method('get')
             ->with('image/ZOY11VC')
@@ -109,7 +108,7 @@ public function testImage()
         $this->assertSame($expectedValue, $api->image('ZOY11VC'));
     }
 
-    public function testUploadWithUrl()
+    public function testUploadWithUrl(): void
     {
         $expectedValue = [
             'data' => true,
@@ -117,7 +116,7 @@ public function testUploadWithUrl()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiImageMock();
         $api->expects($this->once())
             ->method('post')
             ->with('image')
@@ -126,7 +125,7 @@ public function testUploadWithUrl()
         $this->assertSame($expectedValue, $api->upload(['type' => 'url', 'image' => 'http://i.imgur.com/ZOY11VC.png']));
     }
 
-    public function testUploadWithFile()
+    public function testUploadWithFile(): void
     {
         $expectedValue = [
             'data' => true,
@@ -134,7 +133,7 @@ public function testUploadWithFile()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiImageMock();
         $api->expects($this->once())
             ->method('post')
             ->with('image')
@@ -143,23 +142,23 @@ public function testUploadWithFile()
         $this->assertSame($expectedValue, $api->upload(['type' => 'file', 'image' => __DIR__ . '/ZOY11VC.png']));
     }
 
-    public function testUploadWithBadType()
+    public function testUploadWithBadType(): void
     {
         $this->expectException(\Imgur\Exception\InvalidArgumentException::class);
         $this->expectExceptionMessage('is wrong. Possible values are');
 
-        $this->getApiMock()->upload(['type' => 'other', 'image' => 'http://i.imgur.com/ZOY11VC.png']);
+        $this->getApiImageMock()->upload(['type' => 'other', 'image' => 'http://i.imgur.com/ZOY11VC.png']);
     }
 
-    public function testUploadWithUrlParamMissing()
+    public function testUploadWithUrlParamMissing(): void
     {
         $this->expectException(\Imgur\Exception\MissingArgumentException::class);
         $this->expectExceptionMessage('parameters is missing');
 
-        $this->getApiMock()->upload([]);
+        $this->getApiImageMock()->upload([]);
     }
 
-    public function testDeleteImage()
+    public function testDeleteImage(): void
     {
         $expectedValue = [
             'data' => true,
@@ -167,7 +166,7 @@ public function testDeleteImage()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiImageMock();
         $api->expects($this->once())
             ->method('delete')
             ->with('image/ZOY11VC')
@@ -176,7 +175,7 @@ public function testDeleteImage()
         $this->assertSame($expectedValue, $api->deleteImage('ZOY11VC'));
     }
 
-    public function testUpdate()
+    public function testUpdate(): void
     {
         $expectedValue = [
             'data' => true,
@@ -184,7 +183,7 @@ public function testUpdate()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiImageMock();
         $api->expects($this->once())
             ->method('post')
             ->with('image/ZOY11VC')
@@ -193,7 +192,7 @@ public function testUpdate()
         $this->assertSame($expectedValue, $api->update('ZOY11VC', ['title' => 'hihihi']));
     }
 
-    public function testFavorite()
+    public function testFavorite(): void
     {
         $expectedValue = [
             'data' => true,
@@ -201,7 +200,7 @@ public function testFavorite()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiImageMock();
         $api->expects($this->once())
             ->method('post')
             ->with('image/ZOY11VC/favorite')
@@ -209,9 +208,4 @@ public function testFavorite()
 
         $this->assertSame($expectedValue, $api->favorite('ZOY11VC'));
     }
-
-    protected function getApiClass()
-    {
-        return 'Imgur\Api\Image';
-    }
 }
diff --git a/tests/Api/MemegenTest.php b/tests/Api/MemegenTest.php
index 7dcf2f6..53f708b 100644
--- a/tests/Api/MemegenTest.php
+++ b/tests/Api/MemegenTest.php
@@ -12,23 +12,22 @@
 
 class MemegenTest extends ApiTestCase
 {
-    public function testBaseReal()
+    public function testBaseReal(): void
     {
         $this->expectException(\Imgur\Exception\ErrorException::class);
         $this->expectExceptionMessage('Authentication required');
 
-        $guzzleClient = new GuzzleClient(['base_uri' => 'https://api.imgur.com/3/']);
-        $httpClient = new HttpClient([], $guzzleClient);
+        $httpClient = new HttpClient();
         $client = new Client(null, $httpClient);
         $memegen = new Memegen($client);
 
         $memegen->defaultMemes();
     }
 
-    public function testBaseWithResponse()
+    public function testBaseWithResponse(): void
     {
         $mock = new MockHandler([
-            new Response(200, ['Content-Type' => 'application/json'], json_encode([
+            new Response(200, ['Content-Type' => 'application/json'], (string) json_encode([
                 'data' => [
                     [
                         'id' => '2tNR7P7',
@@ -60,7 +59,7 @@ public function testBaseWithResponse()
         $handler = HandlerStack::create($mock);
         $guzzleClient = new GuzzleClient(['handler' => $handler]);
 
-        $httpClient = new HttpClient([], $guzzleClient);
+        $httpClient = new HttpClient([], $guzzleClient, $handler);
         $client = new Client(null, $httpClient);
         $memegen = new Memegen($client);
 
@@ -88,7 +87,7 @@ public function testBaseWithResponse()
         $this->assertArrayHasKey('link', $result[0]);
     }
 
-    public function testMemegen()
+    public function testMemegen(): void
     {
         $expectedValue = [
             'data' => [
@@ -98,7 +97,7 @@ public function testMemegen()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiMemegenMock();
         $api->expects($this->once())
             ->method('get')
             ->with('memegen/defaults')
@@ -106,9 +105,4 @@ public function testMemegen()
 
         $this->assertSame($expectedValue, $api->defaultMemes());
     }
-
-    protected function getApiClass()
-    {
-        return 'Imgur\Api\Memegen';
-    }
 }
diff --git a/tests/Api/NotificationTest.php b/tests/Api/NotificationTest.php
index a8d9663..9ea3518 100644
--- a/tests/Api/NotificationTest.php
+++ b/tests/Api/NotificationTest.php
@@ -12,23 +12,22 @@
 
 class NotificationTest extends ApiTestCase
 {
-    public function testBaseReal()
+    public function testBaseReal(): void
     {
         $this->expectException(\Imgur\Exception\ErrorException::class);
         $this->expectExceptionMessage('Authentication required');
 
-        $guzzleClient = new GuzzleClient(['base_uri' => 'https://api.imgur.com/3/']);
-        $httpClient = new HttpClient([], $guzzleClient);
+        $httpClient = new HttpClient();
         $client = new Client(null, $httpClient);
         $notification = new Notification($client);
 
         $notification->notifications();
     }
 
-    public function testBaseWithResponse()
+    public function testBaseWithResponse(): void
     {
         $mock = new MockHandler([
-            new Response(200, ['Content-Type' => 'application/json'], json_encode([
+            new Response(200, ['Content-Type' => 'application/json'], (string) json_encode([
                 'data' => [
                     'replies' => [],
                     'messages' => [
@@ -60,7 +59,7 @@ public function testBaseWithResponse()
         $handler = HandlerStack::create($mock);
         $guzzleClient = new GuzzleClient(['handler' => $handler]);
 
-        $httpClient = new HttpClient([], $guzzleClient);
+        $httpClient = new HttpClient([], $guzzleClient, $handler);
         $client = new Client(null, $httpClient);
         $notification = new Notification($client);
 
@@ -82,7 +81,7 @@ public function testBaseWithResponse()
         $this->assertArrayHasKey('datetime', $result['messages'][0]['content']);
     }
 
-    public function testNotifications()
+    public function testNotifications(): void
     {
         $expectedValue = [
             'data' => [
@@ -93,7 +92,7 @@ public function testNotifications()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiNotificationMock();
         $api->expects($this->once())
             ->method('get')
             ->with('notification', ['new' => 'true'])
@@ -102,7 +101,27 @@ public function testNotifications()
         $this->assertSame($expectedValue, $api->notifications());
     }
 
-    public function testNotification()
+    public function testNotificationsFalse(): void
+    {
+        $expectedValue = [
+            'data' => [
+                'replies' => [],
+                'messages' => [],
+            ],
+            'success' => true,
+            'status' => 200,
+        ];
+
+        $api = $this->getApiNotificationMock();
+        $api->expects($this->once())
+            ->method('get')
+            ->with('notification', ['new' => 'false'])
+            ->willReturn($expectedValue);
+
+        $this->assertSame($expectedValue, $api->notifications('false'));
+    }
+
+    public function testNotification(): void
     {
         $expectedValue = [
             'data' => [
@@ -112,7 +131,7 @@ public function testNotification()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiNotificationMock();
         $api->expects($this->once())
             ->method('get')
             ->with('notification/76878181')
@@ -121,7 +140,7 @@ public function testNotification()
         $this->assertSame($expectedValue, $api->notification('76878181'));
     }
 
-    public function testNotificationViewed()
+    public function testNotificationViewed(): void
     {
         $expectedValue = [
             'data' => true,
@@ -129,7 +148,7 @@ public function testNotificationViewed()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiNotificationMock();
         $api->expects($this->once())
             ->method('post')
             ->with('notification/76878181')
@@ -137,9 +156,4 @@ public function testNotificationViewed()
 
         $this->assertSame($expectedValue, $api->notificationViewed('76878181'));
     }
-
-    protected function getApiClass()
-    {
-        return 'Imgur\Api\Notification';
-    }
 }
diff --git a/tests/Api/TopicTest.php b/tests/Api/TopicTest.php
index c93369e..9b874cf 100644
--- a/tests/Api/TopicTest.php
+++ b/tests/Api/TopicTest.php
@@ -12,25 +12,24 @@
 
 class TopicTest extends ApiTestCase
 {
-    public function testBaseReal()
+    public function testBaseReal(): void
     {
         $this->expectException(\Imgur\Exception\ErrorException::class);
         $this->expectExceptionMessage('Authentication required');
 
         $this->markTestSkipped('Topic endpoint does not always return 401 with no authentication ...');
 
-        $guzzleClient = new GuzzleClient(['base_uri' => 'https://api.imgur.com/3/']);
-        $httpClient = new HttpClient([], $guzzleClient);
+        $httpClient = new HttpClient();
         $client = new Client(null, $httpClient);
         $topic = new Topic($client);
 
         $topic->defaultTopics();
     }
 
-    public function testBaseWithResponse()
+    public function testBaseWithResponse(): void
     {
         $mock = new MockHandler([
-            new Response(200, ['Content-Type' => 'application/json'], json_encode([
+            new Response(200, ['Content-Type' => 'application/json'], (string) json_encode([
                 'data' => [
                     [
                         'id' => 155,
@@ -107,7 +106,7 @@ public function testBaseWithResponse()
         $handler = HandlerStack::create($mock);
         $guzzleClient = new GuzzleClient(['handler' => $handler]);
 
-        $httpClient = new HttpClient([], $guzzleClient);
+        $httpClient = new HttpClient([], $guzzleClient, $handler);
         $client = new Client(null, $httpClient);
         $topic = new Topic($client);
 
@@ -124,7 +123,7 @@ public function testBaseWithResponse()
         $this->assertArrayHasKey('isHero', $result[0]);
     }
 
-    public function testTopic()
+    public function testTopic(): void
     {
         $expectedValue = [
             'data' => [
@@ -134,7 +133,7 @@ public function testTopic()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiTopicMock();
         $api->expects($this->once())
             ->method('get')
             ->with('topics/defaults')
@@ -143,7 +142,7 @@ public function testTopic()
         $this->assertSame($expectedValue, $api->defaultTopics());
     }
 
-    public function testGalleryTopic()
+    public function testGalleryTopic(): void
     {
         $expectedValue = [
             'data' => [
@@ -153,32 +152,32 @@ public function testGalleryTopic()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiTopicMock();
         $api->expects($this->once())
             ->method('get')
             ->with('topics/155/viral/week/0')
             ->willReturn($expectedValue);
 
-        $this->assertSame($expectedValue, $api->galleryTopic(155));
+        $this->assertSame($expectedValue, $api->galleryTopic('155'));
     }
 
-    public function testGalleryTopicWrongSortValue()
+    public function testGalleryTopicWrongSortValue(): void
     {
         $this->expectException(\Imgur\Exception\InvalidArgumentException::class);
         $this->expectExceptionMessage('is wrong. Possible values are');
 
-        $this->getApiMock()->galleryTopic(155, 'bad sort');
+        $this->getApiTopicMock()->galleryTopic('155', 'bad sort');
     }
 
-    public function testGalleryTopicWrongWindowValue()
+    public function testGalleryTopicWrongWindowValue(): void
     {
         $this->expectException(\Imgur\Exception\InvalidArgumentException::class);
         $this->expectExceptionMessage('is wrong. Possible values are');
 
-        $this->getApiMock()->galleryTopic(155, 'viral', 0, 'bad window');
+        $this->getApiTopicMock()->galleryTopic('155', 'viral', 0, 'bad window');
     }
 
-    public function testGalleryTopicItem()
+    public function testGalleryTopicItem(): void
     {
         $expectedValue = [
             'data' => [
@@ -188,17 +187,12 @@ public function testGalleryTopicItem()
             'status' => 200,
         ];
 
-        $api = $this->getApiMock();
+        $api = $this->getApiTopicMock();
         $api->expects($this->once())
             ->method('get')
             ->with('topics/155/Fbae9SG')
             ->willReturn($expectedValue);
 
-        $this->assertSame($expectedValue, $api->galleryTopicItem(155, 'Fbae9SG'));
-    }
-
-    protected function getApiClass()
-    {
-        return 'Imgur\Api\Topic';
+        $this->assertSame($expectedValue, $api->galleryTopicItem('155', 'Fbae9SG'));
     }
 }
diff --git a/tests/Auth/OAuth2Test.php b/tests/Auth/OAuth2Test.php
index 84062ab..19aa13c 100644
--- a/tests/Auth/OAuth2Test.php
+++ b/tests/Auth/OAuth2Test.php
@@ -13,22 +13,22 @@
 
 class OAuth2Test extends TestCase
 {
-    public function testGetAuthenticationUrl()
+    public function testGetAuthenticationUrl(): void
     {
         $client = new GuzzleClient();
 
-        $auth = new OAuth2(new HttpClient([], $client), 123, 456);
+        $auth = new OAuth2(new HttpClient([], $client), '123', '456');
         $this->assertSame('https://api.imgur.com/oauth2/authorize?client_id=123&response_type=code', $auth->getAuthenticationUrl());
         $this->assertSame('https://api.imgur.com/oauth2/authorize?client_id=123&response_type=pin', $auth->getAuthenticationUrl('pin'));
         $this->assertSame('https://api.imgur.com/oauth2/authorize?client_id=123&response_type=code&state=draft', $auth->getAuthenticationUrl('code', 'draft'));
 
-        $auth = new OAuth2(new HttpClient([], $client), 456, 789);
+        $auth = new OAuth2(new HttpClient([], $client), '456', '789');
         $this->assertSame('https://api.imgur.com/oauth2/authorize?client_id=456&response_type=pin', $auth->getAuthenticationUrl('pin'));
         $this->assertSame('https://api.imgur.com/oauth2/authorize?client_id=456&response_type=code', $auth->getAuthenticationUrl());
         $this->assertSame('https://api.imgur.com/oauth2/authorize?client_id=456&response_type=code&state=draft', $auth->getAuthenticationUrl('code', 'draft'));
     }
 
-    public function testRequestAccessTokenBadStatusCode()
+    public function testRequestAccessTokenBadStatusCode(): void
     {
         $this->expectException(AuthException::class);
         $this->expectExceptionMessage('Request for access token failed');
@@ -39,19 +39,19 @@ public function testRequestAccessTokenBadStatusCode()
         $handler = HandlerStack::create($mock);
         $client = new GuzzleClient(['handler' => $handler]);
 
-        $auth = new OAuth2(new HttpClient([], $client), 123, 456);
+        $auth = new OAuth2(new HttpClient([], $client), '123', '456');
         $auth->requestAccessToken('code', null);
     }
 
-    public function testRequestAccessTokenWithCode()
+    public function testRequestAccessTokenWithCode(): void
     {
         $mock = new MockHandler([
-            new Response(200, ['Content-Type' => 'application/json'], json_encode(['access_token' => 'T0K3N'])),
+            new Response(200, ['Content-Type' => 'application/json'], (string) json_encode(['access_token' => 'T0K3N'])),
         ]);
         $handler = HandlerStack::create($mock);
         $client = new GuzzleClient(['handler' => $handler]);
 
-        $auth = new OAuth2(new HttpClient([], $client), 123, 456);
+        $auth = new OAuth2(new HttpClient([], $client), '123', '456');
         $result = $auth->requestAccessToken('code', null);
 
         $this->assertArrayHasKey('access_token', $result);
@@ -60,15 +60,15 @@ public function testRequestAccessTokenWithCode()
         $this->assertGreaterThanOrEqual(time(), $result['created_at']);
     }
 
-    public function testRequestAccessTokenWithPin()
+    public function testRequestAccessTokenWithPin(): void
     {
         $mock = new MockHandler([
-            new Response(200, ['Content-Type' => 'application/json'], json_encode(['access_token' => 'T0K3N'])),
+            new Response(200, ['Content-Type' => 'application/json'], (string) json_encode(['access_token' => 'T0K3N'])),
         ]);
         $handler = HandlerStack::create($mock);
         $client = new GuzzleClient(['handler' => $handler]);
 
-        $auth = new OAuth2(new HttpClient([], $client), 123, 456);
+        $auth = new OAuth2(new HttpClient([], $client), '123', '456');
         $result = $auth->requestAccessToken('code', 'pin');
 
         $this->assertArrayHasKey('access_token', $result);
@@ -77,81 +77,81 @@ public function testRequestAccessTokenWithPin()
         $this->assertLessThanOrEqual(time(), $result['created_at']);
     }
 
-    public function testRefreshTokenBadStatusCode()
+    public function testRefreshTokenBadStatusCode(): void
     {
         $this->expectException(AuthException::class);
         $this->expectExceptionMessage('Request for refresh access token failed');
 
         $mock = new MockHandler([
-            new Response(400, ['Content-Type' => 'application/json'], json_encode(['data' => ['request' => '/3/account', 'error' => 'oops2', 'method' => 'GET'], 'success' => false, 'status' => 400])),
+            new Response(400, ['Content-Type' => 'application/json'], (string) json_encode(['data' => ['request' => '/3/account', 'error' => 'oops2', 'method' => 'GET'], 'success' => false, 'status' => 400])),
         ]);
         $handler = HandlerStack::create($mock);
         $client = new GuzzleClient(['handler' => $handler]);
 
-        $auth = new OAuth2(new HttpClient([], $client), 123, 456);
+        $auth = new OAuth2(new HttpClient([], $client), '123', '456');
         $auth->refreshToken();
     }
 
-    public function testRefreshToken()
+    public function testRefreshToken(): void
     {
         $mock = new MockHandler([
-            new Response(200, ['Content-Type' => 'application/json'], json_encode(['access_token' => 'T0K3N', 'refresh_token' => 'FR35H'])),
+            new Response(200, ['Content-Type' => 'application/json'], (string) json_encode(['access_token' => 'T0K3N', 'refresh_token' => 'FR35H'])),
         ]);
         $handler = HandlerStack::create($mock);
         $client = new GuzzleClient(['handler' => $handler]);
 
-        $auth = new OAuth2(new HttpClient([], $client), 123, 456);
+        $auth = new OAuth2(new HttpClient([], $client), '123', '456');
         $result = $auth->refreshToken();
 
         $this->assertArrayHasKey('access_token', $result);
         $this->assertSame('T0K3N', $result['access_token']);
     }
 
-    public function testSetAccessTokenNull()
+    public function testSetAccessTokenNull(): void
     {
         $this->expectException(AuthException::class);
         $this->expectExceptionMessage('Token is not a valid json string.');
 
         $client = new GuzzleClient();
-        $auth = new OAuth2(new HttpClient([], $client), 123, 456);
-        $result = $auth->setAccessToken(null);
+        $auth = new OAuth2(new HttpClient([], $client), '123', '456');
+        $auth->setAccessToken(null);
     }
 
-    public function testSetAccessTokenEmpty()
+    public function testSetAccessTokenEmpty(): void
     {
         $this->expectException(AuthException::class);
         $this->expectExceptionMessage('Access token could not be retrieved from the decoded json response.');
 
         $client = new GuzzleClient();
-        $auth = new OAuth2(new HttpClient([], $client), 123, 456);
+        $auth = new OAuth2(new HttpClient([], $client), '123', '456');
         $auth->setAccessToken(['data']);
     }
 
-    public function testCheckAccessTokenExpiredFromScratch()
+    public function testCheckAccessTokenExpiredFromScratch(): void
     {
         $client = new GuzzleClient();
-        $auth = new OAuth2(new HttpClient([], $client), 123, 456);
+        $auth = new OAuth2(new HttpClient([], $client), '123', '456');
         $this->assertTrue($auth->checkAccessTokenExpired());
     }
 
-    public function testCheckAccessTokenExpired()
+    public function testCheckAccessTokenExpired(): void
     {
         $mock = new MockHandler([
-            new Response(200, ['Content-Type' => 'application/json'], json_encode(['access_token' => 'T0K3N', 'expires_in' => 3600])),
+            new Response(200, ['Content-Type' => 'application/json'], (string) json_encode(['access_token' => 'T0K3N', 'expires_in' => 3600])),
         ]);
         $handler = HandlerStack::create($mock);
         $client = new GuzzleClient(['handler' => $handler]);
 
-        $auth = new OAuth2(new HttpClient([], $client), 123, 456);
+        $auth = new OAuth2(new HttpClient([], $client), '123', '456');
         $auth->requestAccessToken('code', null);
 
         $this->assertFalse($auth->checkAccessTokenExpired());
     }
 
-    public function testAuthenticatedRequest()
+    public function testAuthenticatedRequest(): void
     {
         $mock = new MockHandler([
-            new Response(200, ['Content-Type' => 'application/json'], json_encode(['data' => ['access_token' => 'T0K3N', 'expires_in' => 3600]])),
+            new Response(200, ['Content-Type' => 'application/json'], (string) json_encode(['data' => ['access_token' => 'T0K3N', 'expires_in' => 3600]])),
             new Response(200),
         ]);
         $handler = HandlerStack::create($mock);
@@ -159,7 +159,7 @@ public function testAuthenticatedRequest()
 
         $httpClient = new HttpClient([], $client);
 
-        $auth = new OAuth2($httpClient, 123, 456);
+        $auth = new OAuth2($httpClient, '123', '456');
         $auth->requestAccessToken('code', null);
 
         $httpClient->get('http://google.com');
diff --git a/tests/ClientTest.php b/tests/ClientTest.php
index 6fed831..572d99b 100644
--- a/tests/ClientTest.php
+++ b/tests/ClientTest.php
@@ -2,74 +2,100 @@
 
 namespace Imgur\tests;
 
+use Imgur\Auth\OAuth2;
 use Imgur\Client;
 use Imgur\Exception\InvalidArgumentException;
+use Imgur\HttpClient\HttpClient;
+use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
 
 class ClientTest extends TestCase
 {
-    public function testNoParameters()
+    public function testNoParameters(): void
     {
         $client = new Client();
-        $this->assertInstanceOf('Imgur\HttpClient\HttpClient', $client->getHttpClient());
-        $this->assertInstanceOf('Imgur\Auth\OAuth2', $client->getAuthenticationClient());
+        $client->setOption('client_id', 'xx');
+        $client->setOption('client_secret', 'xx');
+
+        $this->assertInstanceOf(HttpClient::class, $client->getHttpClient());
+        $this->assertInstanceOf(OAuth2::class, $client->getAuthenticationClient());
     }
 
-    public function testAuthenticationParameter()
+    public function testAuthenticationParameter(): void
     {
-        $client = new Client($this->getAuthenticationClientMock());
-        $this->assertInstanceOf('Imgur\HttpClient\HttpClient', $client->getHttpClient());
-        $this->assertInstanceOf('Imgur\Auth\AuthInterface', $client->getAuthenticationClient());
+        $authenticationClient = $this->getAuthenticationClientMock();
+        $client = new Client($authenticationClient);
+        $client->setOption('client_id', 'xx');
+        $client->setOption('client_secret', 'xx');
+
+        $this->assertInstanceOf(HttpClient::class, $client->getHttpClient());
+        $this->assertInstanceOf(OAuth2::class, $client->getAuthenticationClient());
     }
 
-    public function testHttpParameter()
+    public function testHttpParameter(): void
     {
-        $client = new Client(null, $this->getHttpClientMock());
-        $this->assertInstanceOf('Imgur\HttpClient\HttpClientInterface', $client->getHttpClient());
-        $this->assertInstanceOf('Imgur\Auth\OAuth2', $client->getAuthenticationClient());
+        $httpClient = $this->getHttpClientMock();
+        $client = new Client(null, $httpClient);
+        $client->setOption('client_id', 'xx');
+        $client->setOption('client_secret', 'xx');
+
+        $this->assertInstanceOf(HttpClient::class, $client->getHttpClient());
+        $this->assertInstanceOf(OAuth2::class, $client->getAuthenticationClient());
     }
 
-    public function testBothParameter()
+    public function testBothParameter(): void
     {
-        $client = new Client($this->getAuthenticationClientMock(), $this->getHttpClientMock());
-        $this->assertInstanceOf('Imgur\HttpClient\HttpClientInterface', $client->getHttpClient());
-        $this->assertInstanceOf('Imgur\Auth\AuthInterface', $client->getAuthenticationClient());
+        $httpClient = $this->getHttpClientMock();
+        $authenticationClient = $this->getAuthenticationClientMock();
+        $client = new Client($authenticationClient, $httpClient);
+        $client->setOption('client_id', 'xx');
+        $client->setOption('client_secret', 'xx');
+
+        $this->assertInstanceOf(HttpClient::class, $client->getHttpClient());
+        $this->assertInstanceOf(OAuth2::class, $client->getAuthenticationClient());
     }
 
     /**
      * @dataProvider getApiClassesProvider
+     *
+     * @param class-string $class
      */
-    public function testGetApiInstance($apiName, $class)
+    public function testGetApiInstance(string $apiName, $class): void
     {
         $client = new Client();
+        $client->setOption('client_id', 'xx');
+        $client->setOption('client_secret', 'xx');
+
         $this->assertInstanceOf($class, $client->api($apiName));
     }
 
-    public function getApiClassesProvider()
+    public function getApiClassesProvider(): array
     {
         return [
-            ['account', 'Imgur\Api\Account'],
-            ['album', 'Imgur\Api\Album'],
-            ['comment', 'Imgur\Api\Comment'],
-            ['gallery', 'Imgur\Api\Gallery'],
-            ['image', 'Imgur\Api\Image'],
-            ['conversation', 'Imgur\Api\Conversation'],
-            ['notification', 'Imgur\Api\Notification'],
-            ['memegen', 'Imgur\Api\Memegen'],
-            ['customGallery', 'Imgur\Api\CustomGallery'],
-            ['topic', 'Imgur\Api\Topic'],
+            ['account', \Imgur\Api\Account::class],
+            ['album', \Imgur\Api\Album::class],
+            ['comment', \Imgur\Api\Comment::class],
+            ['gallery', \Imgur\Api\Gallery::class],
+            ['image', \Imgur\Api\Image::class],
+            ['conversation', \Imgur\Api\Conversation::class],
+            ['notification', \Imgur\Api\Notification::class],
+            ['memegen', \Imgur\Api\Memegen::class],
+            ['customGallery', \Imgur\Api\CustomGallery::class],
+            ['topic', \Imgur\Api\Topic::class],
         ];
     }
 
-    public function testNotGetApiInstance()
+    public function testNotGetApiInstance(): void
     {
         $this->expectException(InvalidArgumentException::class);
 
         $client = new Client();
+        $client->setOption('client_id', 'xx');
+        $client->setOption('client_secret', 'xx');
         $client->api('do_not_exist');
     }
 
-    public function testGetOptionNotDefined()
+    public function testGetOptionNotDefined(): void
     {
         $this->expectException(InvalidArgumentException::class);
 
@@ -77,7 +103,7 @@ public function testGetOptionNotDefined()
         $client->getOption('do_not_exist');
     }
 
-    public function testSetOptionNotDefined()
+    public function testSetOptionNotDefined(): void
     {
         $this->expectException(InvalidArgumentException::class);
 
@@ -88,7 +114,7 @@ public function testSetOptionNotDefined()
     /**
      * @dataProvider getOptions
      */
-    public function testGetOption($option, $value)
+    public function testGetOption(string $option, string $value): void
     {
         $client = new Client();
         $client->setOption($option, $value);
@@ -96,7 +122,7 @@ public function testGetOption($option, $value)
         $this->assertSame($value, $client->getOption($option));
     }
 
-    public function getOptions()
+    public function getOptions(): array
     {
         return [
             ['base_url', 'url'],
@@ -105,23 +131,24 @@ public function getOptions()
         ];
     }
 
-    public function testGetAuthenticationUrl()
+    public function testGetAuthenticationUrl(): void
     {
-        $client = new Client();
-        $this->assertSame('https://api.imgur.com/oauth2/authorize?response_type=code', $client->getAuthenticationUrl());
-        $this->assertSame('https://api.imgur.com/oauth2/authorize?response_type=pin', $client->getAuthenticationUrl('pin'));
-        $this->assertSame('https://api.imgur.com/oauth2/authorize?response_type=code&state=draft', $client->getAuthenticationUrl('code', 'draft'));
+        // $client = new Client();
+        // $this->assertSame('https://api.imgur.com/oauth2/authorize?response_type=code', $client->getAuthenticationUrl());
+        // $this->assertSame('https://api.imgur.com/oauth2/authorize?response_type=pin', $client->getAuthenticationUrl('pin'));
+        // $this->assertSame('https://api.imgur.com/oauth2/authorize?response_type=code&state=draft', $client->getAuthenticationUrl('code', 'draft'));
 
         $client = new Client();
         $client->setOption('client_id', 123);
+        $client->setOption('client_secret', 'xx');
         $this->assertSame('https://api.imgur.com/oauth2/authorize?client_id=123&response_type=pin', $client->getAuthenticationUrl('pin'));
         $this->assertSame('https://api.imgur.com/oauth2/authorize?client_id=123&response_type=code', $client->getAuthenticationUrl());
         $this->assertSame('https://api.imgur.com/oauth2/authorize?client_id=123&response_type=code&state=draft', $client->getAuthenticationUrl('code', 'draft'));
     }
 
-    public function testCheckAccessTokenExpired()
+    public function testCheckAccessTokenExpired(): void
     {
-        $authenticationClient = $this->getAuthenticationClientMock(['checkAccessTokenExpired']);
+        $authenticationClient = $this->getAuthenticationClientMock();
         $authenticationClient->expects($this->once())
             ->method('checkAccessTokenExpired')
             ->with();
@@ -130,7 +157,7 @@ public function testCheckAccessTokenExpired()
         $client->checkAccessTokenExpired();
     }
 
-    public function testRequestAccessToken()
+    public function testRequestAccessToken(): void
     {
         $httpClient = $this->getHttpClientMock();
         $authenticationClient = $this->getAuthenticationClientMock();
@@ -142,7 +169,7 @@ public function testRequestAccessToken()
         $client->requestAccessToken('code');
     }
 
-    public function testRefreshToken()
+    public function testRefreshToken(): void
     {
         $httpClient = $this->getHttpClientMock();
         $authenticationClient = $this->getAuthenticationClientMock();
@@ -153,41 +180,37 @@ public function testRefreshToken()
         $client->refreshToken();
     }
 
-    public function testSetAccessToken()
+    public function testSetAccessToken(): void
     {
         $httpClient = $this->getHttpClientMock();
         $authenticationClient = $this->getAuthenticationClientMock();
         $authenticationClient->expects($this->once())
             ->method('setAccessToken')
-            ->with('token');
+            ->with(['token']);
 
         $client = new Client($authenticationClient, $httpClient);
-        $client->setAccessToken('token');
+        $client->setAccessToken(['token']);
     }
 
-    private function getHttpClientMock(array $methods = [])
+    /**
+     * @return HttpClient&MockObject
+     */
+    private function getHttpClientMock(array $methods = []): object
     {
-        $methods = array_merge(
-            ['get', 'post', 'delete', 'request', 'performRequest', 'createRequest', 'parseResponse'],
-            $methods
-        );
-
-        return $this->getMockBuilder('Imgur\HttpClient\HttpClient')
+        return $this->getMockBuilder(HttpClient::class)
             ->disableOriginalConstructor()
-            ->setMethods($methods)
+            ->onlyMethods(['get', 'post', 'delete', 'performRequest', 'parseResponse'])
+            ->addMethods(array_merge_recursive(['request', 'createRequest'], $methods))
             ->getMock();
     }
 
-    private function getAuthenticationClientMock(array $methods = [])
+    /**
+     * @return OAuth2&MockObject
+     */
+    private function getAuthenticationClientMock()
     {
-        $methods = array_merge(
-            ['getAuthenticationUrl', 'getAccessToken', 'requestAccessToken', 'setAccessToken', 'sign', 'refreshToken'],
-            $methods
-        );
-
         return $this->getMockBuilder('Imgur\Auth\OAuth2')
             ->disableOriginalConstructor()
-            ->setMethods($methods)
             ->getMock();
     }
 }
diff --git a/tests/HttpClient/HttpClientTest.php b/tests/HttpClient/HttpClientTest.php
index 792ba01..acfd1f6 100644
--- a/tests/HttpClient/HttpClientTest.php
+++ b/tests/HttpClient/HttpClientTest.php
@@ -6,12 +6,13 @@
 use GuzzleHttp\Handler\MockHandler;
 use GuzzleHttp\HandlerStack;
 use GuzzleHttp\Psr7\Response;
+use Imgur\Exception\RateLimitException;
 use Imgur\HttpClient\HttpClient;
 use PHPUnit\Framework\TestCase;
 
 class HttpClientTest extends TestCase
 {
-    public function testOptionsToConstructor()
+    public function testOptionsToConstructor(): void
     {
         $httpClient = new TestHttpClient([
             'headers' => ['Cache-Control' => 'no-cache'],
@@ -21,13 +22,13 @@ public function testOptionsToConstructor()
         $this->assertNull($httpClient->getOption('base_uri'));
     }
 
-    public function testDoGETRequest()
+    public function testDoGETRequest(): void
     {
         $path = '/some/path';
         $parameters = ['a' => 'b'];
 
         $mock = new MockHandler([
-            new Response(200, ['Content-Type' => 'application/json'], json_encode(['data' => 'ok !'])),
+            new Response(200, ['Content-Type' => 'application/json'], (string) json_encode(['data' => ['ok !']])),
         ]);
         $handler = HandlerStack::create($mock);
         $client = new GuzzleClient(['handler' => $handler]);
@@ -37,16 +38,16 @@ public function testDoGETRequest()
 
         $result = $httpClient->parseResponse($response);
 
-        $this->assertSame('ok !', $result);
+        $this->assertSame(['ok !'], $result);
     }
 
-    public function testDoPOSTRequest()
+    public function testDoPOSTRequest(): void
     {
         $path = '/some/path';
         $parameters = ['a' => 'b'];
 
         $mock = new MockHandler([
-            new Response(200, ['Content-Type' => 'application/json'], json_encode(['data' => 'ok !'])),
+            new Response(200, ['Content-Type' => 'application/json'], (string) json_encode(['data' => ['ok !']])),
         ]);
         $handler = HandlerStack::create($mock);
         $client = new GuzzleClient(['handler' => $handler]);
@@ -56,10 +57,10 @@ public function testDoPOSTRequest()
 
         $result = $httpClient->parseResponse($response);
 
-        $this->assertSame('ok !', $result);
+        $this->assertSame(['ok !'], $result);
     }
 
-    public function testDoPOSTRequestWithMultipart()
+    public function testDoPOSTRequestWithMultipart(): void
     {
         $path = '/some/path';
         $parameters = [
@@ -68,7 +69,7 @@ public function testDoPOSTRequestWithMultipart()
         ];
 
         $mock = new MockHandler([
-            new Response(200, ['Content-Type' => 'application/json'], json_encode(['data' => 'ok !'])),
+            new Response(200, ['Content-Type' => 'application/json'], (string) json_encode(['data' => ['ok !']])),
         ]);
         $handler = HandlerStack::create($mock);
         $client = new GuzzleClient(['handler' => $handler]);
@@ -78,16 +79,16 @@ public function testDoPOSTRequestWithMultipart()
 
         $result = $httpClient->parseResponse($response);
 
-        $this->assertSame('ok !', $result);
+        $this->assertSame(['ok !'], $result);
     }
 
-    public function testDoPUTRequest()
+    public function testDoPUTRequest(): void
     {
         $path = '/some/path';
         $parameters = ['a' => 'b'];
 
         $mock = new MockHandler([
-            new Response(200, ['Content-Type' => 'application/json'], json_encode(['data' => 'ok !'])),
+            new Response(200, ['Content-Type' => 'application/json'], (string) json_encode(['data' => ['ok !']])),
         ]);
         $handler = HandlerStack::create($mock);
         $client = new GuzzleClient(['handler' => $handler]);
@@ -97,16 +98,16 @@ public function testDoPUTRequest()
 
         $result = $httpClient->parseResponse($response);
 
-        $this->assertSame('ok !', $result);
+        $this->assertSame(['ok !'], $result);
     }
 
-    public function testDoDELETERequest()
+    public function testDoDELETERequest(): void
     {
         $path = '/some/path';
         $parameters = ['a' => 'b'];
 
         $mock = new MockHandler([
-            new Response(200, ['Content-Type' => 'application/json'], json_encode(['data' => 'ok !'])),
+            new Response(200, ['Content-Type' => 'application/json'], (string) json_encode(['data' => ['ok !']])),
         ]);
         $handler = HandlerStack::create($mock);
         $client = new GuzzleClient(['handler' => $handler]);
@@ -116,16 +117,16 @@ public function testDoDELETERequest()
 
         $result = $httpClient->parseResponse($response);
 
-        $this->assertSame('ok !', $result);
+        $this->assertSame(['ok !'], $result);
     }
 
-    public function testDoCustomRequest()
+    public function testDoCustomRequest(): void
     {
         $path = '/some/path';
         $options = ['c' => 'd'];
 
         $mock = new MockHandler([
-            new Response(200, ['Content-Type' => 'application/json'], json_encode(['data' => true])),
+            new Response(200, ['Content-Type' => 'application/json']),
         ]);
         $handler = HandlerStack::create($mock);
         $client = new GuzzleClient(['handler' => $handler]);
@@ -135,12 +136,12 @@ public function testDoCustomRequest()
 
         $result = $httpClient->parseResponse($response);
 
-        $this->assertTrue($result);
+        $this->assertEmpty($result);
     }
 
-    public function testThrowExceptionWhenApiIsExceeded()
+    public function testThrowExceptionWhenApiIsExceeded(): void
     {
-        $this->expectException(\Imgur\Exception\RateLimitException::class);
+        $this->expectException(RateLimitException::class);
         $this->expectExceptionMessage('No user credits available. The limit is 10');
 
         $path = '/some/path';
@@ -148,42 +149,42 @@ public function testThrowExceptionWhenApiIsExceeded()
 
         $mock = new MockHandler([
             new Response(429, [
-                'X-RateLimit-UserLimit' => 10,
-                'X-RateLimit-UserRemaining' => 0,
+                'X-RateLimit-UserLimit' => '10',
+                'X-RateLimit-UserRemaining' => '0',
             ]),
         ]);
         $handler = HandlerStack::create($mock);
         $client = new GuzzleClient(['handler' => $handler]);
 
-        $httpClient = new TestHttpClient([], $client);
+        $httpClient = new TestHttpClient([], $client, $handler);
         $httpClient->get($path, $parameters);
     }
 
-    public function testThrowExceptionWhenClientApiIsExceeded()
+    public function testThrowExceptionWhenClientApiIsExceeded(): void
     {
-        $this->expectException(\Imgur\Exception\RateLimitException::class);
+        $this->expectException(RateLimitException::class);
         $this->expectExceptionMessage('No application credits available. The limit is 10 and will be reset at');
 
         $path = '/some/path';
         $parameters = ['a' => 'b'];
 
         $response = new Response(429, [
-            'X-RateLimit-UserLimit' => 10,
-            'X-RateLimit-UserRemaining' => 10,
-            'X-RateLimit-ClientLimit' => 10,
-            'X-RateLimit-ClientRemaining' => 0,
-            'X-RateLimit-UserReset' => 1474318026,
+            'X-RateLimit-UserLimit' => '10',
+            'X-RateLimit-UserRemaining' => '10',
+            'X-RateLimit-ClientLimit' => '10',
+            'X-RateLimit-ClientRemaining' => '0',
+            'X-RateLimit-UserReset' => '1474318026',
         ]);
 
         $mock = new MockHandler([$response]);
         $handler = HandlerStack::create($mock);
         $client = new GuzzleClient(['handler' => $handler]);
 
-        $httpClient = new TestHttpClient([], $client);
+        $httpClient = new TestHttpClient([], $client, $handler);
         $httpClient->get($path, $parameters);
     }
 
-    public function testThrowExceptionWhenBadRequestPlainError()
+    public function testThrowExceptionWhenBadRequestPlainError(): void
     {
         $this->expectException(\Imgur\Exception\RuntimeException::class);
         $this->expectExceptionMessage('oops');
@@ -192,21 +193,21 @@ public function testThrowExceptionWhenBadRequestPlainError()
         $parameters = ['a' => 'b'];
 
         $response = new Response(429, [
-            'X-RateLimit-UserLimit' => 10,
-            'X-RateLimit-UserRemaining' => 10,
-            'X-RateLimit-ClientLimit' => 10,
-            'X-RateLimit-ClientRemaining' => 10,
+            'X-RateLimit-UserLimit' => '10',
+            'X-RateLimit-UserRemaining' => '10',
+            'X-RateLimit-ClientLimit' => '10',
+            'X-RateLimit-ClientRemaining' => '10',
         ], 'oops');
 
         $mock = new MockHandler([$response]);
         $handler = HandlerStack::create($mock);
         $client = new GuzzleClient(['handler' => $handler]);
 
-        $httpClient = new TestHttpClient([], $client);
+        $httpClient = new TestHttpClient([], $client, $handler);
         $httpClient->get($path, $parameters);
     }
 
-    public function testThrowExceptionWhenBadRequestJsonError()
+    public function testThrowExceptionWhenBadRequestJsonError(): void
     {
         $this->expectException(\Imgur\Exception\ErrorException::class);
         $this->expectExceptionMessage('Request to: /3/account failed with: "oops2"');
@@ -215,21 +216,21 @@ public function testThrowExceptionWhenBadRequestJsonError()
         $parameters = ['a' => 'b'];
 
         $response = new Response(429, [
-            'X-RateLimit-UserLimit' => 10,
-            'X-RateLimit-UserRemaining' => 10,
-            'X-RateLimit-ClientLimit' => 10,
-            'X-RateLimit-ClientRemaining' => 10,
-        ], json_encode(['data' => ['request' => '/3/account', 'error' => 'oops2', 'method' => 'GET'], 'success' => false, 'status' => 403]));
+            'X-RateLimit-UserLimit' => '10',
+            'X-RateLimit-UserRemaining' => '10',
+            'X-RateLimit-ClientLimit' => '10',
+            'X-RateLimit-ClientRemaining' => '10',
+        ], (string) json_encode(['data' => ['request' => '/3/account', 'error' => 'oops2', 'method' => 'GET'], 'success' => false, 'status' => 403]));
 
         $mock = new MockHandler([$response]);
         $handler = HandlerStack::create($mock);
         $client = new GuzzleClient(['handler' => $handler]);
 
-        $httpClient = new TestHttpClient([], $client);
+        $httpClient = new TestHttpClient([], $client, $handler);
         $httpClient->get($path, $parameters);
     }
 
-    public function testThrowExceptionWhenBadRequestNoClientMock()
+    public function testThrowExceptionWhenBadRequestNoClientMock(): void
     {
         $this->expectException(\Imgur\Exception\RuntimeException::class);
         $this->expectExceptionMessage('oops');
@@ -238,21 +239,21 @@ public function testThrowExceptionWhenBadRequestNoClientMock()
         $parameters = ['a' => 'b'];
 
         $response = new Response(429, [
-            'X-RateLimit-UserLimit' => 10,
-            'X-RateLimit-UserRemaining' => 10,
-            'X-RateLimit-ClientLimit' => 10,
-            'X-RateLimit-ClientRemaining' => 10,
+            'X-RateLimit-UserLimit' => '10',
+            'X-RateLimit-UserRemaining' => '10',
+            'X-RateLimit-ClientLimit' => '10',
+            'X-RateLimit-ClientRemaining' => '10',
         ], 'oops');
 
         $mock = new MockHandler([$response]);
         $handler = HandlerStack::create($mock);
         $client = new GuzzleClient(['handler' => $handler]);
 
-        $httpClient = new HttpClient([], $client);
+        $httpClient = new HttpClient([], $client, $handler);
         $httpClient->get($path, $parameters);
     }
 
-    // public function testThrowLogicException()
+    // public function testThrowLogicException(): void
     // {
     //     $this->expectException(\Imgur\Exception\ErrorException::class);
     //
@@ -288,7 +289,10 @@ public function testThrowExceptionWhenBadRequestNoClientMock()
 
 class TestHttpClient extends HttpClient
 {
-    public function getOption($name, $default = null)
+    /**
+     * @return array|string|null
+     */
+    public function getOption(string $name, string $default = null)
     {
         return isset($this->options[$name]) ? $this->options[$name] : $default;
     }
diff --git a/tests/Middleware/AuthMiddlewareTest.php b/tests/Middleware/AuthMiddlewareTest.php
index 040c777..a274db4 100644
--- a/tests/Middleware/AuthMiddlewareTest.php
+++ b/tests/Middleware/AuthMiddlewareTest.php
@@ -14,9 +14,9 @@
 
 class AuthMiddlewareTest extends TestCase
 {
-    public function testDefineClientIdOnBadToken()
+    public function testDefineClientIdOnBadToken(): void
     {
-        $token = 'token';
+        $token = ['token'];
         $clientId = 'clientid';
 
         $mock = new MockHandler([
@@ -39,7 +39,7 @@ function (RequestInterface $request, array $options) {
         $this->assertInstanceOf(PromiseInterface::class, $promise);
     }
 
-    public function testDefineBeareOnGoodToken()
+    public function testDefineBeareOnGoodToken(): void
     {
         $token = ['access_token' => 'T0K3N'];
         $clientId = 'clientid';
diff --git a/tests/Middleware/ErrorMiddlewareTest.php b/tests/Middleware/ErrorMiddlewareTest.php
index c49f36c..458d7f5 100644
--- a/tests/Middleware/ErrorMiddlewareTest.php
+++ b/tests/Middleware/ErrorMiddlewareTest.php
@@ -6,13 +6,14 @@
 use GuzzleHttp\HandlerStack;
 use GuzzleHttp\Psr7\Request;
 use GuzzleHttp\Psr7\Response;
+use Imgur\Exception\ErrorException;
 use Imgur\Exception\RateLimitException;
 use Imgur\Middleware\ErrorMiddleware;
 use PHPUnit\Framework\TestCase;
 
 class ErrorMiddlewareTest extends TestCase
 {
-    public function testNothinHappenOnOKResponse()
+    public function testNothinHappenOnOKResponse(): void
     {
         $mock = new MockHandler([
             new Response(200),
@@ -28,15 +29,15 @@ public function testNothinHappenOnOKResponse()
         $this->assertSame(200, $response->getStatusCode());
     }
 
-    public function testRateLimitUser()
+    public function testRateLimitUser(): void
     {
         $this->expectException(RateLimitException::class);
         $this->expectExceptionMessage('No user credits available. The limit is 10');
 
         $mock = new MockHandler([
             new Response(429, [
-                'X-RateLimit-UserRemaining' => 0,
-                'X-RateLimit-UserLimit' => 10,
+                'X-RateLimit-UserRemaining' => '0',
+                'X-RateLimit-UserLimit' => '10',
             ]),
         ]);
         $stack = new HandlerStack($mock);
@@ -47,18 +48,18 @@ public function testRateLimitUser()
         $handler($request, [])->wait();
     }
 
-    public function testRateLimitClient()
+    public function testRateLimitClient(): void
     {
         $this->expectException(RateLimitException::class);
         $this->expectExceptionMessage('No application credits available. The limit is 10 and will be reset at 2015-09-04');
 
         $mock = new MockHandler([
             new Response(429, [
-                'X-RateLimit-UserRemaining' => 9,
-                'X-RateLimit-UserLimit' => 10,
-                'X-RateLimit-ClientRemaining' => 0,
-                'X-RateLimit-ClientLimit' => 10,
-                'X-RateLimit-UserReset' => 1441401387, // 4/9/2015  23:16:27
+                'X-RateLimit-UserRemaining' => '9',
+                'X-RateLimit-UserLimit' => '10',
+                'X-RateLimit-ClientRemaining' => '0',
+                'X-RateLimit-ClientLimit' => '10',
+                'X-RateLimit-UserReset' => '1441401387', // 4/9/2015  23:16:27
             ]),
         ]);
         $stack = new HandlerStack($mock);
@@ -69,18 +70,18 @@ public function testRateLimitClient()
         $handler($request, [])->wait();
     }
 
-    public function testErrorOverCapacity()
+    public function testErrorOverCapacity(): void
     {
-        $this->expectException(\Imgur\Exception\ErrorException::class);
+        $this->expectException(ErrorException::class);
         $this->expectExceptionMessage('Request failed with: "Imgur is temporarily over capacity. Please try again later."');
 
         $mock = new MockHandler([
             new Response(429, [
-                'X-RateLimit-UserRemaining' => 9,
-                'X-RateLimit-UserLimit' => 10,
-                'X-RateLimit-ClientRemaining' => 9,
-                'X-RateLimit-ClientLimit' => 10,
-            ], json_encode(['status' => 500, 'success' => false, 'data' => ['error' => 'Imgur is temporarily over capacity. Please try again later.']])),
+                'X-RateLimit-UserRemaining' => '9',
+                'X-RateLimit-UserLimit' => '10',
+                'X-RateLimit-ClientRemaining' => '9',
+                'X-RateLimit-ClientLimit' => '10',
+            ], (string) json_encode(['status' => 500, 'success' => false, 'data' => ['error' => 'Imgur is temporarily over capacity. Please try again later.']])),
         ]);
         $stack = new HandlerStack($mock);
         $stack->push(ErrorMiddleware::error());
@@ -90,18 +91,18 @@ public function testErrorOverCapacity()
         $handler($request, [])->wait();
     }
 
-    public function testErrorUploadingTooFast()
+    public function testErrorUploadingTooFast(): void
     {
-        $this->expectException(\Imgur\Exception\ErrorException::class);
+        $this->expectException(ErrorException::class);
         $this->expectExceptionMessage('Request to: /3/image.json failed with: "You are uploading too fast. Please wait 59 more minutes."');
 
         $mock = new MockHandler([
             new Response(429, [
-                'X-RateLimit-UserRemaining' => 9,
-                'X-RateLimit-UserLimit' => 10,
-                'X-RateLimit-ClientRemaining' => 9,
-                'X-RateLimit-ClientLimit' => 10,
-            ], json_encode(['status' => 400, 'success' => false, 'data' => ['error' => ['code' => 429, 'message' => 'You are uploading too fast. Please wait 59 more minutes.', 'type' => 'ImgurException', 'exception' => []], 'request' => '/3/image.json', 'method' => 'POST']])),
+                'X-RateLimit-UserRemaining' => '9',
+                'X-RateLimit-UserLimit' => '10',
+                'X-RateLimit-ClientRemaining' => '9',
+                'X-RateLimit-ClientLimit' => '10',
+            ], (string) json_encode(['status' => 400, 'success' => false, 'data' => ['error' => ['code' => 429, 'message' => 'You are uploading too fast. Please wait 59 more minutes.', 'type' => 'ImgurException', 'exception' => []], 'request' => '/3/image.json', 'method' => 'POST']])),
         ]);
         $stack = new HandlerStack($mock);
         $stack->push(ErrorMiddleware::error());
@@ -111,18 +112,18 @@ public function testErrorUploadingTooFast()
         $handler($request, [])->wait();
     }
 
-    public function testErrorNoMessageInError()
+    public function testErrorNoMessageInError(): void
     {
-        $this->expectException(\Imgur\Exception\ErrorException::class);
+        $this->expectException(ErrorException::class);
         $this->expectExceptionMessage('Request to: /3/image.json failed with: "Error code: 666"');
 
         $mock = new MockHandler([
             new Response(429, [
-                'X-RateLimit-UserRemaining' => 9,
-                'X-RateLimit-UserLimit' => 10,
-                'X-RateLimit-ClientRemaining' => 9,
-                'X-RateLimit-ClientLimit' => 10,
-            ], json_encode(['status' => 400, 'success' => false, 'data' => ['error' => ['code' => 666, 'type' => 'ImgurException', 'exception' => []], 'request' => '/3/image.json', 'method' => 'POST']])),
+                'X-RateLimit-UserRemaining' => '9',
+                'X-RateLimit-UserLimit' => '10',
+                'X-RateLimit-ClientRemaining' => '9',
+                'X-RateLimit-ClientLimit' => '10',
+            ], (string) json_encode(['status' => 400, 'success' => false, 'data' => ['error' => ['code' => 666, 'type' => 'ImgurException', 'exception' => []], 'request' => '/3/image.json', 'method' => 'POST']])),
         ]);
         $stack = new HandlerStack($mock);
         $stack->push(ErrorMiddleware::error());
@@ -132,18 +133,18 @@ public function testErrorNoMessageInError()
         $handler($request, [])->wait();
     }
 
-    public function testErrorWithJson()
+    public function testErrorWithJson(): void
     {
-        $this->expectException(\Imgur\Exception\ErrorException::class);
+        $this->expectException(ErrorException::class);
         $this->expectExceptionMessage('Request to: /here failed with: "oops"');
 
         $mock = new MockHandler([
             new Response(429, [
-                'X-RateLimit-UserRemaining' => 9,
-                'X-RateLimit-UserLimit' => 10,
-                'X-RateLimit-ClientRemaining' => 9,
-                'X-RateLimit-ClientLimit' => 10,
-            ], json_encode(['data' => ['request' => '/here', 'error' => 'oops']])),
+                'X-RateLimit-UserRemaining' => '9',
+                'X-RateLimit-UserLimit' => '10',
+                'X-RateLimit-ClientRemaining' => '9',
+                'X-RateLimit-ClientLimit' => '10',
+            ], (string) json_encode(['data' => ['request' => '/here', 'error' => 'oops']])),
         ]);
         $stack = new HandlerStack($mock);
         $stack->push(ErrorMiddleware::error());
@@ -153,17 +154,17 @@ public function testErrorWithJson()
         $handler($request, [])->wait();
     }
 
-    public function testErrorWithoutJson()
+    public function testErrorWithoutJson(): void
     {
         $this->expectException(\Imgur\Exception\RuntimeException::class);
         $this->expectExceptionMessage('hihi');
 
         $mock = new MockHandler([
             new Response(429, [
-                'X-RateLimit-UserRemaining' => 9,
-                'X-RateLimit-UserLimit' => 10,
-                'X-RateLimit-ClientRemaining' => 9,
-                'X-RateLimit-ClientLimit' => 10,
+                'X-RateLimit-UserRemaining' => '9',
+                'X-RateLimit-UserLimit' => '10',
+                'X-RateLimit-ClientRemaining' => '9',
+                'X-RateLimit-ClientLimit' => '10',
             ], 'hihi'),
         ]);
         $stack = new HandlerStack($mock);
@@ -174,16 +175,16 @@ public function testErrorWithoutJson()
         $handler($request, [])->wait();
     }
 
-    public function testRateLimitPost()
+    public function testRateLimitPost(): void
     {
         $this->expectException(RateLimitException::class);
         $this->expectExceptionMessage('No post credits available. The limit is 10 and will be reset at 2015-09-04');
 
         $mock = new MockHandler([
             new Response(429, [
-                'X-Post-Rate-Limit-Remaining' => 0,
-                'X-Post-Rate-Limit-Limit' => 10,
-                'X-Post-Rate-Limit-Reset' => 1441401387, // 4/9/2015  23:16:27
+                'X-Post-Rate-Limit-Remaining' => '0',
+                'X-Post-Rate-Limit-Limit' => '10',
+                'X-Post-Rate-Limit-Reset' => '1441401387', // 4/9/2015  23:16:27
             ]),
         ]);
         $stack = new HandlerStack($mock);