From c73473a627dcc23f28c7b4f4117a9303a0b82059 Mon Sep 17 00:00:00 2001
From: David Buchmann <david.buchmann@liip.ch>
Date: Sun, 24 Mar 2024 11:18:23 +0100
Subject: [PATCH] strict typing

---
 .phpstan/classAliases.php                     | 22 -----
 phpstan.neon.dist                             |  2 -
 src/CacheInvalidator.php                      | 57 ++++---------
 src/EventListener/LogListener.php             | 17 ++--
 src/Exception/ExceptionCollection.php         | 31 +++----
 src/Exception/InvalidUrlException.php         | 16 ++--
 src/Exception/MissingHostException.php        |  4 +-
 src/Exception/ProxyResponseException.php      |  5 +-
 src/Exception/ProxyUnreachableException.php   |  5 +-
 .../UnsupportedProxyOperationException.php    |  4 +-
 src/ProxyClient/Cloudflare.php                | 29 +++----
 src/ProxyClient/Dispatcher.php                | 11 ++-
 src/ProxyClient/Fastly.php                    | 18 ++--
 src/ProxyClient/HttpDispatcher.php            | 53 ++++--------
 src/ProxyClient/HttpProxyClient.php           | 40 ++++-----
 src/ProxyClient/Invalidation/BanCapable.php   | 22 ++---
 src/ProxyClient/Invalidation/ClearCapable.php |  4 +-
 src/ProxyClient/Invalidation/PurgeCapable.php | 10 +--
 .../Invalidation/RefreshCapable.php           | 10 +--
 src/ProxyClient/Invalidation/TagCapable.php   |  6 +-
 src/ProxyClient/MultiplexerClient.php         | 71 +++++-----------
 src/ProxyClient/Nginx.php                     | 13 ++-
 src/ProxyClient/Noop.php                      | 14 ++--
 src/ProxyClient/ProxyClient.php               |  2 +-
 src/ProxyClient/Symfony.php                   | 13 ++-
 src/ProxyClient/Varnish.php                   | 25 +++---
 src/ResponseTagger.php                        | 41 ++++-----
 src/SymfonyCache/AccessControlledListener.php | 13 +--
 src/SymfonyCache/CleanupCacheTagsListener.php |  9 +-
 src/SymfonyCache/CustomTtlListener.php        | 24 +++---
 src/SymfonyCache/DebugListener.php            |  9 +-
 .../EventDispatchingHttpCache.php             |  6 +-
 src/SymfonyCache/HttpCacheAware.php           | 12 +--
 src/SymfonyCache/HttpCacheProvider.php        |  5 +-
 src/SymfonyCache/KernelDispatcher.php         |  2 +-
 src/SymfonyCache/PurgeListener.php            | 14 +---
 src/SymfonyCache/PurgeTagsListener.php        | 19 ++---
 src/SymfonyCache/RefreshListener.php          |  2 +-
 src/SymfonyCache/UserContextListener.php      | 14 +---
 .../CommaSeparatedTagHeaderFormatter.php      | 26 ++----
 .../MaxHeaderValueLengthFormatter.php         | 33 +++-----
 src/TagHeaderFormatter/TagHeaderFormatter.php |  6 +-
 src/TagHeaderFormatter/TagHeaderParser.php    |  2 +-
 src/Test/CacheAssertions.php                  |  8 +-
 .../EventDispatchingHttpCacheTestCase.php     | 29 +++----
 src/Test/HttpCaller.php                       | 23 ++---
 src/Test/HttpClient.php                       | 46 +++-------
 src/Test/NginxTest.php                        | 40 +++------
 .../PHPUnit/AbstractCacheConstraintTrait.php  | 20 ++---
 src/Test/PHPUnit/IsCacheHitConstraint.php     |  2 +-
 src/Test/PHPUnit/IsCacheMissConstraint.php    |  2 +-
 src/Test/Proxy/AbstractProxy.php              | 73 ++++------------
 src/Test/Proxy/NginxProxy.php                 | 33 +++-----
 src/Test/Proxy/ProxyInterface.php             |  6 +-
 src/Test/Proxy/SymfonyProxy.php               | 24 ++----
 src/Test/Proxy/VarnishProxy.php               | 84 +++++--------------
 src/Test/SymfonyTest.php                      | 32 ++-----
 src/Test/VarnishTest.php                      | 51 ++++-------
 src/UserContext/AnonymousRequestMatcher.php   |  7 +-
 src/UserContext/DefaultHashGenerator.php      |  8 +-
 src/UserContext/HashGenerator.php             |  7 +-
 src/UserContext/UserContext.php               | 22 +++--
 .../Varnish/UserContextFailureTest.php        | 12 ++-
 .../Varnish/UserContextNocacheTest.php        | 12 ++-
 tests/Unit/ProxyClient/HttpDispatcherTest.php | 11 ---
 tests/Unit/ResponseTaggerTest.php             | 20 +++--
 tests/Unit/Test/Proxy/AbstractProxyTest.php   | 12 +--
 tests/Unit/Test/Proxy/VarnishProxyTest.php    | 18 ++--
 68 files changed, 444 insertions(+), 899 deletions(-)
 delete mode 100644 .phpstan/classAliases.php

diff --git a/.phpstan/classAliases.php b/.phpstan/classAliases.php
deleted file mode 100644
index 2eb016467..000000000
--- a/.phpstan/classAliases.php
+++ /dev/null
@@ -1,22 +0,0 @@
-<?php
-
-use FOS\HttpCache\SymfonyCache\CacheInvalidation;
-use FOS\HttpCache\SymfonyCache\Compatibility\CacheInvalidationS6;
-use FOS\HttpCache\SymfonyCache\Compatibility\CacheInvalidationLegacy;
-
-/*
- * Hint phpstan on the class aliases. 
- * Symfony 6 introduced a BC break in the signature of the protected method HttpKernelInterface::fetch.
- * Load the correct interface to match the signature.
- */
-if (version_compare(PHP_VERSION, '8.1.0', '>=')) {
-    class_alias(
-        CacheInvalidationS6::class,
-        CacheInvalidation::class
-    );
-} else {
-    class_alias(
-        CacheInvalidationLegacy::class,
-        CacheInvalidation::class
-    );
-}
\ No newline at end of file
diff --git a/phpstan.neon.dist b/phpstan.neon.dist
index ac6edee46..3fe08f90d 100644
--- a/phpstan.neon.dist
+++ b/phpstan.neon.dist
@@ -2,8 +2,6 @@ parameters:
     level: 1
     paths:
         - src
-    bootstrapFiles:
-        - .phpstan/classAliases.php
     excludePaths:
         analyseAndScan:
             # contains code to support legacy phpunit versions
diff --git a/src/CacheInvalidator.php b/src/CacheInvalidator.php
index 41e808a43..1523d8111 100644
--- a/src/CacheInvalidator.php
+++ b/src/CacheInvalidator.php
@@ -61,21 +61,10 @@ class CacheInvalidator
      */
     public const CLEAR = 'clear';
 
-    /**
-     * @var ProxyClient
-     */
-    private $cache;
+    private ProxyClient $cache;
 
-    /**
-     * @var EventDispatcherInterface
-     */
-    private $eventDispatcher;
+    private EventDispatcherInterface $eventDispatcher;
 
-    /**
-     * Constructor.
-     *
-     * @param ProxyClient $cache HTTP cache
-     */
     public function __construct(ProxyClient $cache)
     {
         $this->cache = $cache;
@@ -91,11 +80,9 @@ public function __construct(ProxyClient $cache)
      *
      * @param string $operation one of the class constants
      *
-     * @return bool
-     *
      * @throws InvalidArgumentException
      */
-    public function supports(string $operation)
+    public function supports(string $operation): bool
     {
         switch ($operation) {
             case self::PATH:
@@ -125,7 +112,7 @@ public function supports(string $operation)
      */
     public function setEventDispatcher(EventDispatcherInterface $eventDispatcher): void
     {
-        if ($this->eventDispatcher) {
+        if (isset($this->eventDispatcher)) {
             // if you want to set a custom event dispatcher, do so right after instantiating
             // the invalidator.
             throw new \Exception('You may not change the event dispatcher once it is set.');
@@ -135,12 +122,10 @@ public function setEventDispatcher(EventDispatcherInterface $eventDispatcher): v
 
     /**
      * Get the event dispatcher used by the cache invalidator.
-     *
-     * @return EventDispatcherInterface
      */
-    public function getEventDispatcher()
+    public function getEventDispatcher(): EventDispatcherInterface
     {
-        if (!$this->eventDispatcher) {
+        if (!isset($this->eventDispatcher)) {
             $this->eventDispatcher = new EventDispatcher();
         }
 
@@ -150,14 +135,12 @@ public function getEventDispatcher()
     /**
      * Invalidate a path or URL.
      *
-     * @param string $path    Path or URL
-     * @param array  $headers HTTP headers (optional)
-     *
-     * @return $this
+     * @param string                $path    Path or URL
+     * @param array<string, string> $headers HTTP headers (optional)
      *
      * @throws UnsupportedProxyOperationException
      */
-    public function invalidatePath($path, array $headers = []): static
+    public function invalidatePath(string $path, array $headers = []): static
     {
         if (!$this->cache instanceof PurgeCapable) {
             throw UnsupportedProxyOperationException::cacheDoesNotImplement('PURGE');
@@ -171,16 +154,14 @@ public function invalidatePath($path, array $headers = []): static
     /**
      * Refresh a path or URL.
      *
-     * @param string $path    Path or URL
-     * @param array  $headers HTTP headers (optional)
+     * @param string                $path    Path or URL
+     * @param array<string, string> $headers HTTP headers (optional)
      *
      * @see RefreshCapable::refresh()
      *
-     * @return $this
-     *
      * @throws UnsupportedProxyOperationException
      */
-    public function refreshPath($path, array $headers = []): static
+    public function refreshPath(string $path, array $headers = []): static
     {
         if (!$this->cache instanceof RefreshCapable) {
             throw UnsupportedProxyOperationException::cacheDoesNotImplement('REFRESH');
@@ -199,9 +180,7 @@ public function refreshPath($path, array $headers = []): static
      *
      * @see BanCapable::ban()
      *
-     * @param array $headers HTTP headers that path must match to be banned
-     *
-     * @return $this
+     * @param array<string, string> $headers HTTP headers that path must match to be banned
      *
      * @throws UnsupportedProxyOperationException If HTTP cache does not support BAN requests
      */
@@ -221,9 +200,7 @@ public function invalidate(array $headers): static
      *
      * @see TagCapable::tags()
      *
-     * @param array $tags Tags that should be removed/expired from the cache. An empty tag list is ignored.
-     *
-     * @return $this
+     * @param string[] $tags Tags that should be removed/expired from the cache. An empty tag list is ignored.
      *
      * @throws UnsupportedProxyOperationException If HTTP cache does not support Tags invalidation
      */
@@ -257,8 +234,6 @@ public function invalidateTags(array $tags): static
      * @param array|string|null $hosts       Regular expression of a host name or list of
      *                                       exact host names to limit banning
      *
-     * @return $this
-     *
      * @throws UnsupportedProxyOperationException If HTTP cache does not support BAN requests
      *
      *@see BanCapable::banPath()
@@ -277,8 +252,6 @@ public function invalidateRegex(string $path, ?string $contentType = null, array
     /**
      * Clear the cache completely.
      *
-     * @return $this
-     *
      * @throws UnsupportedProxyOperationException if HTTP cache does not support clearing the cache completely
      */
     public function clearCache(): static
@@ -299,7 +272,7 @@ public function clearCache(): static
      *
      * @throws ExceptionCollection if any errors occurred during flush
      */
-    public function flush()
+    public function flush(): int
     {
         try {
             return $this->cache->flush();
diff --git a/src/EventListener/LogListener.php b/src/EventListener/LogListener.php
index 477574b26..a8031d681 100644
--- a/src/EventListener/LogListener.php
+++ b/src/EventListener/LogListener.php
@@ -22,10 +22,7 @@
  */
 class LogListener implements EventSubscriberInterface
 {
-    /**
-     * @var LoggerInterface
-     */
-    private $logger;
+    private LoggerInterface $logger;
 
     public function __construct(LoggerInterface $logger)
     {
@@ -40,22 +37,22 @@ public static function getSubscribedEvents(): array
         ];
     }
 
-    public function onProxyUnreachableError(Event $event)
+    public function onProxyUnreachableError(Event $event): void
     {
-        $this->log(LogLevel::CRITICAL, $event->getException());
+        $this->log($event->getException());
     }
 
-    public function onProxyResponseError(Event $event)
+    public function onProxyResponseError(Event $event): void
     {
-        $this->log(LogLevel::CRITICAL, $event->getException());
+        $this->log($event->getException());
     }
 
-    private function log($level, \Exception $exception)
+    private function log(\Throwable $exception): void
     {
         $context = [
             'exception' => $exception,
         ];
 
-        $this->logger->log($level, $exception->getMessage(), $context);
+        $this->logger->log(LogLevel::CRITICAL, $exception->getMessage(), $context);
     }
 }
diff --git a/src/Exception/ExceptionCollection.php b/src/Exception/ExceptionCollection.php
index d3ae2389f..eec0651a1 100644
--- a/src/Exception/ExceptionCollection.php
+++ b/src/Exception/ExceptionCollection.php
@@ -17,8 +17,14 @@
  */
 class ExceptionCollection extends \Exception implements \IteratorAggregate, \Countable, HttpCacheException
 {
-    private $exceptions = [];
+    /**
+     * @var \Throwable[]
+     */
+    private array $exceptions = [];
 
+    /**
+     * @param \Throwable[] $exceptions
+     */
     public function __construct(array $exceptions = [])
     {
         foreach ($exceptions as $exception) {
@@ -28,10 +34,8 @@ public function __construct(array $exceptions = [])
 
     /**
      * Add an exception to the collection.
-     *
-     * @return $this
      */
-    public function add(\Exception $e)
+    public function add(\Throwable $e): static
     {
         if (!$this->message) {
             $this->message = $e->getMessage();
@@ -44,34 +48,25 @@ public function add(\Exception $e)
 
     /**
      * Get first exception in collection or null, if there is none.
-     *
-     * @return \Exception|null
      */
-    public function getFirst()
+    public function getFirst(): ?\Throwable
     {
         if ($this->count() > 0) {
             return $this->exceptions[0];
         }
+
+        return null;
     }
 
-    /**
-     * Get exception iterator.
-     *
-     * @return \ArrayIterator
-     */
-    #[\ReturnTypeWillChange]
-    public function getIterator()
+    public function getIterator(): \ArrayIterator
     {
         return new \ArrayIterator($this->exceptions);
     }
 
     /**
      * Get number of exceptions in collection.
-     *
-     * @return int
      */
-    #[\ReturnTypeWillChange]
-    public function count()
+    public function count(): int
     {
         return count($this->exceptions);
     }
diff --git a/src/Exception/InvalidUrlException.php b/src/Exception/InvalidUrlException.php
index 48f33293e..475faf94c 100644
--- a/src/Exception/InvalidUrlException.php
+++ b/src/Exception/InvalidUrlException.php
@@ -17,12 +17,10 @@
 class InvalidUrlException extends InvalidArgumentException
 {
     /**
-     * @param string $url    the invalid URL
-     * @param string $reason Further explanation why the URL was invalid (optional)
-     *
-     * @return self
+     * @param string      $url    the invalid URL
+     * @param string|null $reason Further explanation why the URL was invalid (optional)
      */
-    public static function invalidUrl($url, $reason = null)
+    public static function invalidUrl(string $url, ?string $reason = null): InvalidUrlException
     {
         $msg = sprintf('URL "%s" is invalid.', $url);
         if ($reason) {
@@ -33,12 +31,10 @@ public static function invalidUrl($url, $reason = null)
     }
 
     /**
-     * @param string $server  Invalid server
-     * @param array  $allowed Allowed URL parts
-     *
-     * @return self
+     * @param string   $server  Invalid server
+     * @param string[] $allowed Allowed URL parts
      */
-    public static function invalidUrlParts($server, array $allowed)
+    public static function invalidUrlParts(string $server, array $allowed): InvalidUrlException
     {
         return new self(sprintf(
             'Server "%s" is invalid. Only %s URL parts are allowed.',
diff --git a/src/Exception/MissingHostException.php b/src/Exception/MissingHostException.php
index 10babeb0b..6bd312a40 100644
--- a/src/Exception/MissingHostException.php
+++ b/src/Exception/MissingHostException.php
@@ -19,10 +19,8 @@ class MissingHostException extends \RuntimeException implements HttpCacheExcepti
 {
     /**
      * @param string $path the path that was asked to be invalidated
-     *
-     * @return MissingHostException
      */
-    public static function missingHost($path)
+    public static function missingHost(string $path): MissingHostException
     {
         $msg = sprintf(
             'Path "%s" cannot be invalidated without a host. '
diff --git a/src/Exception/ProxyResponseException.php b/src/Exception/ProxyResponseException.php
index f6181e827..c2d9dd2db 100644
--- a/src/Exception/ProxyResponseException.php
+++ b/src/Exception/ProxyResponseException.php
@@ -18,10 +18,7 @@
  */
 class ProxyResponseException extends \RuntimeException implements HttpCacheException
 {
-    /**
-     * @return ProxyResponseException
-     */
-    public static function proxyResponse(HttpException $exception)
+    public static function proxyResponse(HttpException $exception): ProxyResponseException
     {
         $message = sprintf(
             '%s error response "%s" from caching proxy',
diff --git a/src/Exception/ProxyUnreachableException.php b/src/Exception/ProxyUnreachableException.php
index 09c6744a2..81dc8bba9 100644
--- a/src/Exception/ProxyUnreachableException.php
+++ b/src/Exception/ProxyUnreachableException.php
@@ -19,10 +19,7 @@
  */
 class ProxyUnreachableException extends \RuntimeException implements HttpCacheException
 {
-    /**
-     * @return ProxyUnreachableException
-     */
-    public static function proxyUnreachable(NetworkException $requestException)
+    public static function proxyUnreachable(NetworkException $requestException): ProxyUnreachableException
     {
         $message = sprintf(
             'Request to caching proxy at %s failed with message "%s"',
diff --git a/src/Exception/UnsupportedProxyOperationException.php b/src/Exception/UnsupportedProxyOperationException.php
index 2d3500550..d8f76ffba 100644
--- a/src/Exception/UnsupportedProxyOperationException.php
+++ b/src/Exception/UnsupportedProxyOperationException.php
@@ -19,10 +19,8 @@ class UnsupportedProxyOperationException extends \RuntimeException implements Ht
 {
     /**
      * @param string $method name of the HTTP method that would be required
-     *
-     * @return UnsupportedProxyOperationException
      */
-    public static function cacheDoesNotImplement($method)
+    public static function cacheDoesNotImplement(string $method): UnsupportedProxyOperationException
     {
         return new self(sprintf('HTTP cache does not support %s requests', $method));
     }
diff --git a/src/ProxyClient/Cloudflare.php b/src/ProxyClient/Cloudflare.php
index 89089138d..b2535e070 100644
--- a/src/ProxyClient/Cloudflare.php
+++ b/src/ProxyClient/Cloudflare.php
@@ -15,6 +15,8 @@
 use FOS\HttpCache\ProxyClient\Invalidation\PurgeCapable;
 use FOS\HttpCache\ProxyClient\Invalidation\TagCapable;
 use Http\Message\RequestFactory;
+use Psr\Http\Message\UriInterface;
+use Symfony\Component\OptionsResolver\OptionsResolver;
 
 /**
  * Cloudflare HTTP cache invalidator.
@@ -47,10 +49,10 @@ class Cloudflare extends HttpProxyClient implements ClearCapable, PurgeCapable,
      *
      * @var array<string|array{url: string, headers: string[]}>
      */
-    private $purgeByUrlsData = [];
+    private array $purgeByUrlsData = [];
 
     public function __construct(
-        Dispatcher $httpDispatcher,
+        Dispatcher $dispatcher,
         array $options = [],
         ?RequestFactory $messageFactory = null
     ) {
@@ -58,7 +60,7 @@ public function __construct(
             throw new \Exception('ext-json is required for cloudflare invalidation');
         }
 
-        parent::__construct($httpDispatcher, $options, $messageFactory);
+        parent::__construct($dispatcher, $options, $messageFactory);
     }
 
     /**
@@ -68,7 +70,7 @@ public function __construct(
      *
      * @see https://api.cloudflare.com/#zone-purge-files-by-cache-tags,-host-or-prefix
      */
-    public function invalidateTags(array $tags)
+    public function invalidateTags(array $tags): static
     {
         if (!$tags) {
             return $this;
@@ -89,7 +91,7 @@ public function invalidateTags(array $tags)
      * @see https://api.cloudflare.com/#zone-purge-files-by-url
      * @see https://developers.cloudflare.com/cache/how-to/purge-cache#purge-by-single-file-by-url For details on headers you can pass to clear the cache correctly
      */
-    public function purge($url, array $headers = [])
+    public function purge(string $url, array $headers = []): static
     {
         if (!empty($headers)) {
             $this->purgeByUrlsData[] = [
@@ -106,7 +108,7 @@ public function purge($url, array $headers = [])
     /**
      * @see https://api.cloudflare.com/#zone-purge-all-files
      */
-    public function clear()
+    public function clear(): static
     {
         $this->queueRequest(
             'POST',
@@ -119,10 +121,7 @@ public function clear()
         return $this;
     }
 
-    /**
-     * {@inheritdoc} Queue requests for purge by URLs
-     */
-    public function flush()
+    public function flush(): int
     {
         // Queue requests for purge by URL
         foreach (\array_chunk($this->purgeByUrlsData, self::URL_BATCH_PURGE_LIMIT) as $urlChunk) {
@@ -140,9 +139,11 @@ public function flush()
     }
 
     /**
-     * {@inheritdoc} Always provides authentication token
+     * {@inheritdoc}
+     *
+     * Always provides authentication token
      */
-    protected function queueRequest($method, $url, array $headers, $validateHost = true, $body = null)
+    protected function queueRequest(string $method, UriInterface|string $url, array $headers, bool $validateHost = true, $body = null): void
     {
         parent::queueRequest(
             $method,
@@ -153,7 +154,7 @@ protected function queueRequest($method, $url, array $headers, $validateHost = t
         );
     }
 
-    protected function configureOptions()
+    protected function configureOptions(): OptionsResolver
     {
         $resolver = parent::configureOptions();
 
@@ -167,7 +168,7 @@ protected function configureOptions()
 
     private function json_encode(array $data): string
     {
-        $json = json_encode($data, JSON_UNESCAPED_SLASHES);
+        $json = json_encode($data, JSON_THROW_ON_ERROR | JSON_UNESCAPED_SLASHES);
         if (false === $json) {
             throw new \InvalidArgumentException(sprintf('Cannot encode "$data": %s', json_last_error_msg()));
         }
diff --git a/src/ProxyClient/Dispatcher.php b/src/ProxyClient/Dispatcher.php
index 160a24424..47874f6ea 100644
--- a/src/ProxyClient/Dispatcher.php
+++ b/src/ProxyClient/Dispatcher.php
@@ -25,12 +25,11 @@ interface Dispatcher
     /**
      * Queue invalidation request.
      *
-     * @param bool $validateHost If false, do not validate
-     *                           that we either have a base
-     *                           uri or the invalidation
-     *                           request specifies the host
+     * @param bool $validateHost If false, do not validate that we either have
+     *                           a base uri or the invalidation request
+     *                           specifies the host
      */
-    public function invalidate(RequestInterface $invalidationRequest, $validateHost = true);
+    public function invalidate(RequestInterface $invalidationRequest, bool $validateHost = true);
 
     /**
      * Send all pending invalidation requests and make sure the requests have
@@ -41,5 +40,5 @@ public function invalidate(RequestInterface $invalidationRequest, $validateHost
      *
      * @throws ExceptionCollection If any errors occurred during flush
      */
-    public function flush();
+    public function flush(): int;
 }
diff --git a/src/ProxyClient/Fastly.php b/src/ProxyClient/Fastly.php
index 459fb7764..97aacf6f8 100644
--- a/src/ProxyClient/Fastly.php
+++ b/src/ProxyClient/Fastly.php
@@ -16,6 +16,8 @@
 use FOS\HttpCache\ProxyClient\Invalidation\RefreshCapable;
 use FOS\HttpCache\ProxyClient\Invalidation\TagCapable;
 use Http\Message\RequestFactory;
+use Psr\Http\Message\UriInterface;
+use Symfony\Component\OptionsResolver\OptionsResolver;
 
 /**
  * Fastly HTTP cache invalidator.
@@ -46,7 +48,7 @@ class Fastly extends HttpProxyClient implements ClearCapable, PurgeCapable, Refr
     private const API_ENDPOINT = 'https://api.fastly.com';
 
     public function __construct(
-        Dispatcher $httpDispatcher,
+        Dispatcher $dispatcher,
         array $options = [],
         ?RequestFactory $messageFactory = null
     ) {
@@ -54,13 +56,13 @@ public function __construct(
             throw new \Exception('ext-json is required for fastly invalidation');
         }
 
-        parent::__construct($httpDispatcher, $options, $messageFactory);
+        parent::__construct($dispatcher, $options, $messageFactory);
     }
 
     /**
      * @see https://docs.fastly.com/api/purge#purge_db35b293f8a724717fcf25628d713583
      */
-    public function invalidateTags(array $tags)
+    public function invalidateTags(array $tags): static
     {
         if (!$tags) {
             return $this;
@@ -90,7 +92,7 @@ public function invalidateTags(array $tags)
      * @see https://docs.fastly.com/api/purge#soft_purge_0c4f56f3d68e9bed44fb8b638b78ea36
      * @see https://docs.fastly.com/guides/purging/authenticating-api-purge-requests#purging-urls-with-an-api-token
      */
-    public function purge($url, array $headers = [])
+    public function purge(string $url, array $headers = []): static
     {
         if (true === $this->options['soft_purge']) {
             $headers['Fastly-Soft-Purge'] = 1;
@@ -106,7 +108,7 @@ public function purge($url, array $headers = [])
         return $this;
     }
 
-    public function refresh($url, array $headers = [])
+    public function refresh(string $url, array $headers = []): static
     {
         // First soft purge url
         $this->queueRequest(
@@ -134,7 +136,7 @@ public function refresh($url, array $headers = [])
      * - Does not support soft purge, for that use an "all" key.
      * - Requires a API token of a user with at least Engineer permissions.
      */
-    public function clear()
+    public function clear(): static
     {
         $this->queueRequest(
             'POST',
@@ -149,7 +151,7 @@ public function clear()
     /**
      * {@inheritdoc} Always provides default authentication token on "Fastly-Key" header.
      */
-    protected function queueRequest($method, $url, array $headers, $validateHost = true, $body = null)
+    protected function queueRequest(string $method, UriInterface|string $url, array $headers, bool $validateHost = true, $body = null): void
     {
         parent::queueRequest(
             $method,
@@ -160,7 +162,7 @@ protected function queueRequest($method, $url, array $headers, $validateHost = t
         );
     }
 
-    protected function configureOptions()
+    protected function configureOptions(): OptionsResolver
     {
         $resolver = parent::configureOptions();
 
diff --git a/src/ProxyClient/HttpDispatcher.php b/src/ProxyClient/HttpDispatcher.php
index e209b7b01..571cf568a 100644
--- a/src/ProxyClient/HttpDispatcher.php
+++ b/src/ProxyClient/HttpDispatcher.php
@@ -36,36 +36,27 @@
  */
 class HttpDispatcher implements Dispatcher
 {
-    /**
-     * @var HttpAsyncClient
-     */
-    private $httpClient;
-
-    /**
-     * @var UriFactory
-     */
-    private $uriFactory;
+    private HttpAsyncClient $httpClient;
+    private UriFactory $uriFactory;
 
     /**
      * Queued requests.
      *
      * @var RequestInterface[]
      */
-    private $queue = [];
+    private array $queue = [];
 
     /**
      * Caching proxy server host names or IP addresses.
      *
      * @var UriInterface[]
      */
-    private $servers;
+    private array $servers;
 
     /**
      * Application host name and optional base URL.
-     *
-     * @var UriInterface
      */
-    private $baseUri;
+    private ?UriInterface $baseUri;
 
     /**
      * If you specify a custom HTTP client, make sure that it converts HTTP
@@ -90,7 +81,7 @@ class HttpDispatcher implements Dispatcher
      */
     public function __construct(
         array $servers,
-        $baseUri = '',
+        string $baseUri = '',
         ?HttpAsyncClient $httpClient = null,
         ?UriFactory $uriFactory = null
     ) {
@@ -107,7 +98,7 @@ public function __construct(
         $this->setBaseUri($baseUri);
     }
 
-    public function invalidate(RequestInterface $invalidationRequest, $validateHost = true)
+    public function invalidate(RequestInterface $invalidationRequest, bool $validateHost = true): void
     {
         if ($validateHost && !$this->baseUri && !$invalidationRequest->getUri()->getHost()) {
             throw MissingHostException::missingHost((string) $invalidationRequest->getUri());
@@ -122,7 +113,7 @@ public function invalidate(RequestInterface $invalidationRequest, $validateHost
         $this->queue[$signature] = $invalidationRequest;
     }
 
-    public function flush()
+    public function flush(): int
     {
         $queue = $this->queue;
         $this->queue = [];
@@ -167,7 +158,7 @@ public function flush()
      *
      * @return UriInterface[]
      */
-    protected function getServers()
+    protected function getServers(): array
     {
         return $this->servers;
     }
@@ -179,7 +170,7 @@ protected function getServers()
      *
      * @return RequestInterface[]
      */
-    private function fanOut(RequestInterface $request)
+    private function fanOut(RequestInterface $request): array
     {
         $requests = [];
 
@@ -244,7 +235,7 @@ private function fanOut(RequestInterface $request)
      * @throws InvalidUrlException If server is invalid or contains URL
      *                             parts other than scheme, host, port
      */
-    private function setServers(array $servers)
+    private function setServers(array $servers): void
     {
         $this->servers = [];
         foreach ($servers as $server) {
@@ -256,11 +247,11 @@ private function setServers(array $servers)
      * Set application base URI that will be prefixed to relative purge and
      * refresh requests, and validate it.
      *
-     * @param string $uriString Your application’s base URI
+     * @param string|null $uriString Your application’s base URI
      *
      * @throws InvalidUrlException If the base URI is not a valid URI
      */
-    private function setBaseUri($uriString = null)
+    private function setBaseUri(?string $uriString = null): void
     {
         if (!$uriString) {
             $this->baseUri = null;
@@ -277,7 +268,6 @@ private function setBaseUri($uriString = null)
      * Prefix the URL with "http://" if it has no scheme, then check the URL
      * for validity. You can specify what parts of the URL are allowed.
      *
-     * @param string   $uriString
      * @param string[] $allowedParts Array of allowed URL parts (optional)
      *
      * @return UriInterface Filtered URI (with default scheme if there was no scheme)
@@ -285,19 +275,12 @@ private function setBaseUri($uriString = null)
      * @throws InvalidUrlException If URL is invalid, the scheme is not http or
      *                             contains parts that are not expected
      */
-    private function filterUri($uriString, array $allowedParts = [])
+    private function filterUri(string $uriString, array $allowedParts = []): UriInterface
     {
-        if (!is_string($uriString)) {
-            throw new \InvalidArgumentException(sprintf(
-                'URI parameter must be a string, %s given',
-                gettype($uriString)
-            ));
-        }
-
         // Creating a PSR-7 URI without scheme (with parse_url) results in the
         // original hostname to be seen as path. So first add a scheme if none
         // is given.
-        if (false === strpos($uriString, '://')) {
+        if (!str_contains($uriString, '://')) {
             $uriString = sprintf('%s://%s', 'http', $uriString);
         }
 
@@ -327,12 +310,8 @@ private function filterUri($uriString, array $allowedParts = [])
      * for the same requests.
      *
      * This signature is used to avoid sending the same invalidation request twice.
-     *
-     * @param RequestInterface $request An invalidation request
-     *
-     * @return string A signature for this request
      */
-    private function getRequestSignature(RequestInterface $request)
+    private function getRequestSignature(RequestInterface $request): string
     {
         $headers = $request->getHeaders();
         ksort($headers);
diff --git a/src/ProxyClient/HttpProxyClient.php b/src/ProxyClient/HttpProxyClient.php
index 104f7bc7a..299b1d3a1 100644
--- a/src/ProxyClient/HttpProxyClient.php
+++ b/src/ProxyClient/HttpProxyClient.php
@@ -26,54 +26,45 @@ abstract class HttpProxyClient implements ProxyClient
 {
     /**
      * Dispatcher for invalidation HTTP requests.
-     *
-     * @var HttpDispatcher
      */
-    private $httpDispatcher;
+    private Dispatcher $httpDispatcher;
 
-    /**
-     * @var RequestFactory
-     */
-    private $requestFactory;
+    private RequestFactory $requestFactory;
 
     /**
      * The options configured in the constructor argument or default values.
      *
      * @var array The resolved options
      */
-    protected $options;
+    protected array $options;
 
     /**
-     * Constructor.
-     *
      * The base class has no options.
      *
-     * @param Dispatcher          $httpDispatcher Helper to send HTTP requests to caching proxy
+     * @param Dispatcher          $dispatcher     Helper to send instructions to the caching proxy
      * @param array               $options        Options for this client
      * @param RequestFactory|null $messageFactory Factory for PSR-7 messages. If none supplied,
      *                                            a default one is created
      */
     public function __construct(
-        Dispatcher $httpDispatcher,
+        Dispatcher $dispatcher,
         array $options = [],
         ?RequestFactory $messageFactory = null
     ) {
-        $this->httpDispatcher = $httpDispatcher;
+        $this->httpDispatcher = $dispatcher;
         $this->options = $this->configureOptions()->resolve($options);
         $this->requestFactory = $messageFactory ?: MessageFactoryDiscovery::find();
     }
 
-    public function flush()
+    public function flush(): int
     {
         return $this->httpDispatcher->flush();
     }
 
     /**
      * Get options resolver with default settings.
-     *
-     * @return OptionsResolver
      */
-    protected function configureOptions()
+    protected function configureOptions(): OptionsResolver
     {
         return new OptionsResolver();
     }
@@ -81,12 +72,11 @@ protected function configureOptions()
     /**
      * Create a request and queue it with the HTTP dispatcher.
      *
-     * @param string                               $method
-     * @param string|UriInterface                  $url
+     * @param array<string, string>                $headers
      * @param bool                                 $validateHost see Dispatcher::invalidate
      * @param resource|string|StreamInterface|null $body
      */
-    protected function queueRequest($method, $url, array $headers, $validateHost = true, $body = null)
+    protected function queueRequest(string $method, UriInterface|string $url, array $headers, bool $validateHost = true, $body = null): void
     {
         $this->httpDispatcher->invalidate(
             $this->requestFactory->createRequest($method, $url, $headers, $body),
@@ -106,13 +96,13 @@ protected function queueRequest($method, $url, array $headers, $validateHost = t
      * collisions would in the worst case lead to unintended invalidations,
      * which is not a bug.
      *
-     * @param array $tags The tags to escape
+     * @param string[] $tags The tags to escape
      *
-     * @return array Sane tags
+     * @return string[] Sane tags
      */
-    protected function escapeTags(array $tags)
+    protected function escapeTags(array $tags): array
     {
-        array_walk($tags, function (&$tag) {
+        array_walk($tags, static function (&$tag) {
             // WARNING: changing the list of characters that are escaped is a BC break for existing installations,
             // as existing tags on the cache would not be invalidated anymore if they contain a character that is
             // newly escaped
@@ -132,7 +122,7 @@ protected function escapeTags(array $tags)
      *
      * @return int Number of tags per tag invalidation request
      */
-    protected function determineTagsPerHeader($escapedTags, $glue)
+    protected function determineTagsPerHeader(array $escapedTags, string $glue): int
     {
         if (mb_strlen(implode($glue, $escapedTags)) < $this->options['header_length']) {
             return count($escapedTags);
diff --git a/src/ProxyClient/Invalidation/BanCapable.php b/src/ProxyClient/Invalidation/BanCapable.php
index f556d27b3..30a612edc 100644
--- a/src/ProxyClient/Invalidation/BanCapable.php
+++ b/src/ProxyClient/Invalidation/BanCapable.php
@@ -35,11 +35,9 @@ interface BanCapable extends ProxyClient
      * host name, configure your proxy to copy the host to a custom HTTP header
      * such as X-Host.
      *
-     * @param array $headers HTTP headers that path must match to be banned
-     *
-     * @return $this
+     * @param array<string, string> $headers HTTP headers that path must match to be banned
      */
-    public function ban(array $headers);
+    public function ban(array $headers): static;
 
     /**
      * Ban URLs based on a regular expression for the URI, an optional
@@ -65,14 +63,12 @@ public function ban(array $headers);
      *
      *    $client->banPath('*.png$', null, '^www.example.com$');
      *
-     * @param string       $path        regular expression pattern for URI to
-     *                                  invalidate
-     * @param string       $contentType regular expression pattern for the content
-     *                                  type to limit banning, for instance 'text'
-     * @param array|string $hosts       regular expression of a host name or list
-     *                                  of exact host names to limit banning
-     *
-     * @return $this
+     * @param string            $path        regular expression pattern for URI to
+     *                                       invalidate
+     * @param string|null       $contentType regular expression pattern for the content
+     *                                       type to limit banning, for instance 'text'
+     * @param array|string|null $hosts       regular expression of a host name or list
+     *                                       of exact host names to limit banning
      */
-    public function banPath($path, $contentType = null, $hosts = null);
+    public function banPath(string $path, ?string $contentType = null, array|string|null $hosts = null): static;
 }
diff --git a/src/ProxyClient/Invalidation/ClearCapable.php b/src/ProxyClient/Invalidation/ClearCapable.php
index 750d62fac..bec7b3956 100644
--- a/src/ProxyClient/Invalidation/ClearCapable.php
+++ b/src/ProxyClient/Invalidation/ClearCapable.php
@@ -24,8 +24,6 @@ interface ClearCapable extends ProxyClient
 {
     /**
      * Remove all cache items from this cache.
-     *
-     * @return $this
      */
-    public function clear();
+    public function clear(): static;
 }
diff --git a/src/ProxyClient/Invalidation/PurgeCapable.php b/src/ProxyClient/Invalidation/PurgeCapable.php
index ade75e312..17ccd0939 100644
--- a/src/ProxyClient/Invalidation/PurgeCapable.php
+++ b/src/ProxyClient/Invalidation/PurgeCapable.php
@@ -36,11 +36,9 @@ interface PurgeCapable extends ProxyClient
      * Please note that purge will invalidate all variants, so you do not need
      * to specify variants headers, such as ``Accept``.
      *
-     * @param string $url     Path or URL to purge
-     * @param array  $headers Extra HTTP headers to send to the caching proxy
-     *                        (optional)
-     *
-     * @return $this
+     * @param string                $url     Path or URL to purge
+     * @param array<string, string> $headers Extra HTTP headers to send to the caching proxy
+     *                                       (optional)
      */
-    public function purge($url, array $headers = []);
+    public function purge(string $url, array $headers = []): static;
 }
diff --git a/src/ProxyClient/Invalidation/RefreshCapable.php b/src/ProxyClient/Invalidation/RefreshCapable.php
index 3b0e5bb00..deb25decd 100644
--- a/src/ProxyClient/Invalidation/RefreshCapable.php
+++ b/src/ProxyClient/Invalidation/RefreshCapable.php
@@ -47,11 +47,9 @@ interface RefreshCapable extends ProxyClient
      *        ->flush()
      *    ;
      *
-     * @param string $url     Path or URL to refresh
-     * @param array  $headers Extra HTTP headers to send to the caching proxy
-     *                        (optional)
-     *
-     * @return $this
+     * @param string                $url     Path or URL to refresh
+     * @param array<string, string> $headers Extra HTTP headers to send to the caching proxy
+     *                                       (optional)
      */
-    public function refresh($url, array $headers = []);
+    public function refresh(string $url, array $headers = []): static;
 }
diff --git a/src/ProxyClient/Invalidation/TagCapable.php b/src/ProxyClient/Invalidation/TagCapable.php
index 0ed19a59c..23f131442 100644
--- a/src/ProxyClient/Invalidation/TagCapable.php
+++ b/src/ProxyClient/Invalidation/TagCapable.php
@@ -25,9 +25,7 @@ interface TagCapable extends ProxyClient
     /**
      * Remove/Expire cache objects based on cache tags.
      *
-     * @param array $tags Tags that should be removed/expired from the cache. An empty tag list should be ignored.
-     *
-     * @return $this
+     * @param string[] $tags Tags that should be removed/expired from the cache. An empty tag list should be ignored.
      */
-    public function invalidateTags(array $tags);
+    public function invalidateTags(array $tags): static;
 }
diff --git a/src/ProxyClient/MultiplexerClient.php b/src/ProxyClient/MultiplexerClient.php
index b8d35ab3a..e31d5bc53 100644
--- a/src/ProxyClient/MultiplexerClient.php
+++ b/src/ProxyClient/MultiplexerClient.php
@@ -11,7 +11,6 @@
 
 namespace FOS\HttpCache\ProxyClient;
 
-use FOS\HttpCache\Exception\ExceptionCollection;
 use FOS\HttpCache\Exception\InvalidArgumentException;
 use FOS\HttpCache\ProxyClient\Invalidation\BanCapable;
 use FOS\HttpCache\ProxyClient\Invalidation\ClearCapable;
@@ -29,7 +28,7 @@ class MultiplexerClient implements BanCapable, PurgeCapable, RefreshCapable, Tag
     /**
      * @var ProxyClient[]
      */
-    private $proxyClients;
+    private array $proxyClients;
 
     /**
      * MultiplexerClient constructor.
@@ -41,8 +40,7 @@ public function __construct(array $proxyClients)
         foreach ($proxyClients as $proxyClient) {
             if (!$proxyClient instanceof ProxyClient) {
                 throw new InvalidArgumentException(
-                    'Expected ProxyClientInterface, got: '.
-                    (is_object($proxyClient) ? get_class($proxyClient) : gettype($proxyClient))
+                    'Expected ProxyClientInterface, got: '.get_debug_type($proxyClient)
                 );
             }
         }
@@ -50,31 +48,14 @@ public function __construct(array $proxyClients)
         $this->proxyClients = $proxyClients;
     }
 
-    /**
-     * Forwards to all clients.
-     *
-     * @param array $headers HTTP headers that path must match to be banned
-     *
-     * @return $this
-     */
-    public function ban(array $headers)
+    public function ban(array $headers): static
     {
         $this->invoke(BanCapable::class, 'ban', [$headers]);
 
         return $this;
     }
 
-    /**
-     * Forwards to all clients.
-     *
-     * @param string       $path        Regular expression pattern for URI to invalidate
-     * @param string       $contentType Regular expression pattern for the content type to limit banning, for instance
-     *                                  'text'
-     * @param array|string $hosts       Regular expression of a host name or list of exact host names to limit banning
-     *
-     * @return $this
-     */
-    public function banPath($path, $contentType = null, $hosts = null)
+    public function banPath(string $path, ?string $contentType = null, array|string|null $hosts = null): static
     {
         $this->invoke(BanCapable::class, 'banPath', [$path, $contentType, $hosts]);
 
@@ -82,13 +63,11 @@ public function banPath($path, $contentType = null, $hosts = null)
     }
 
     /**
-     * Forwards to all clients.
-     *
-     * @return int The number of cache invalidations performed per caching server
+     * {@inheritDoc}
      *
-     * @throws ExceptionCollection If any errors occurred during flush
+     * Forwards to all clients.
      */
-    public function flush()
+    public function flush(): int
     {
         $count = 0;
         foreach ($this->proxyClients as $proxyClient) {
@@ -102,10 +81,8 @@ public function flush()
      * Forwards tag invalidation request to all clients.
      *
      * {@inheritdoc}
-     *
-     * @return $this
      */
-    public function invalidateTags(array $tags)
+    public function invalidateTags(array $tags): static
     {
         if (!$tags) {
             return $this;
@@ -119,12 +96,9 @@ public function invalidateTags(array $tags)
     /**
      * Forwards to all clients.
      *
-     * @param string $url     Path or URL to purge
-     * @param array  $headers Extra HTTP headers to send to the caching proxy (optional)
-     *
-     * @return $this
+     * {@inheritdoc}
      */
-    public function purge($url, array $headers = [])
+    public function purge(string $url, array $headers = []): static
     {
         $this->invoke(PurgeCapable::class, 'purge', [$url, $headers]);
 
@@ -134,12 +108,9 @@ public function purge($url, array $headers = [])
     /**
      * Forwards to all clients.
      *
-     * @param string $url     Path or URL to refresh
-     * @param array  $headers Extra HTTP headers to send to the caching proxy (optional)
-     *
-     * @return $this
+     * {@inheritdoc}
      */
-    public function refresh($url, array $headers = [])
+    public function refresh(string $url, array $headers = []): static
     {
         $this->invoke(RefreshCapable::class, 'refresh', [$url, $headers]);
 
@@ -149,9 +120,9 @@ public function refresh($url, array $headers = [])
     /**
      * Forwards to all clients.
      *
-     * @return $this
+     * {@inheritdoc}
      */
-    public function clear()
+    public function clear(): static
     {
         $this->invoke(ClearCapable::class, 'clear', []);
 
@@ -162,11 +133,11 @@ public function clear()
      * Invoke the given $method on all available ProxyClients implementing the
      * given $interface.
      *
-     * @param string $interface The FQN of the interface
-     * @param string $method    The method to invoke
-     * @param array  $arguments The arguments to be passed to the method
+     * @param string       $interface The FQN of the interface
+     * @param string       $method    The method to invoke
+     * @param array<mixed> $arguments The arguments to be passed to the method
      */
-    private function invoke($interface, $method, array $arguments)
+    private function invoke(string $interface, string $method, array $arguments): void
     {
         foreach ($this->getProxyClients($interface) as $proxyClient) {
             call_user_func_array([$proxyClient, $method], $arguments);
@@ -176,15 +147,15 @@ private function invoke($interface, $method, array $arguments)
     /**
      * Get proxy clients that implement a feature interface.
      *
-     * @param string $interface
+     * @param class-string $interface
      *
      * @return ProxyClient[]
      */
-    private function getProxyClients($interface)
+    private function getProxyClients(string $interface): array
     {
         return array_filter(
             $this->proxyClients,
-            function ($proxyClient) use ($interface) {
+            static function ($proxyClient) use ($interface) {
                 return is_subclass_of($proxyClient, $interface);
             }
         );
diff --git a/src/ProxyClient/Nginx.php b/src/ProxyClient/Nginx.php
index 97deb240c..b3b695ce5 100644
--- a/src/ProxyClient/Nginx.php
+++ b/src/ProxyClient/Nginx.php
@@ -13,6 +13,7 @@
 
 use FOS\HttpCache\ProxyClient\Invalidation\PurgeCapable;
 use FOS\HttpCache\ProxyClient\Invalidation\RefreshCapable;
+use Symfony\Component\OptionsResolver\OptionsResolver;
 
 /**
  * NGINX HTTP cache invalidator.
@@ -31,7 +32,7 @@ class Nginx extends HttpProxyClient implements PurgeCapable, RefreshCapable
 
     public const HTTP_HEADER_REFRESH = 'X-Refresh';
 
-    public function refresh($url, array $headers = [])
+    public function refresh(string $url, array $headers = []): static
     {
         $headers = array_merge($headers, [self::HTTP_HEADER_REFRESH => '1']);
         $this->queueRequest(self::HTTP_METHOD_REFRESH, $url, $headers);
@@ -39,7 +40,7 @@ public function refresh($url, array $headers = [])
         return $this;
     }
 
-    public function purge($url, array $headers = [])
+    public function purge(string $url, array $headers = []): static
     {
         $purgeUrl = $this->buildPurgeUrl($url);
         $this->queueRequest(self::HTTP_METHOD_PURGE, $purgeUrl, $headers);
@@ -47,7 +48,7 @@ public function purge($url, array $headers = [])
         return $this;
     }
 
-    protected function configureOptions()
+    protected function configureOptions(): OptionsResolver
     {
         $resolver = parent::configureOptions();
         $resolver->setDefaults(['purge_location' => false]);
@@ -57,12 +58,8 @@ protected function configureOptions()
 
     /**
      * Create the correct URL to purge a resource.
-     *
-     * @param string $url URL
-     *
-     * @return string Rewritten URL
      */
-    private function buildPurgeUrl($url)
+    private function buildPurgeUrl(string $url): string
     {
         if (!$this->options['purge_location']) {
             return $url;
diff --git a/src/ProxyClient/Noop.php b/src/ProxyClient/Noop.php
index 2d00ff0fd..904b7c4b7 100644
--- a/src/ProxyClient/Noop.php
+++ b/src/ProxyClient/Noop.php
@@ -28,37 +28,37 @@
  */
 class Noop implements ProxyClient, BanCapable, PurgeCapable, RefreshCapable, TagCapable, ClearCapable
 {
-    public function ban(array $headers)
+    public function ban(array $headers): static
     {
         return $this;
     }
 
-    public function banPath($path, $contentType = null, $hosts = null)
+    public function banPath(string $path, ?string $contentType = null, array|string|null $hosts = null): static
     {
         return $this;
     }
 
-    public function invalidateTags(array $tags)
+    public function invalidateTags(array $tags): static
     {
         return $this;
     }
 
-    public function purge($url, array $headers = [])
+    public function purge(string $url, array $headers = []): static
     {
         return $this;
     }
 
-    public function refresh($url, array $headers = [])
+    public function refresh(string $url, array $headers = []): static
     {
         return $this;
     }
 
-    public function flush()
+    public function flush(): int
     {
         return 0;
     }
 
-    public function clear()
+    public function clear(): static
     {
         return $this;
     }
diff --git a/src/ProxyClient/ProxyClient.php b/src/ProxyClient/ProxyClient.php
index 3f3f924e8..fdeb9d694 100644
--- a/src/ProxyClient/ProxyClient.php
+++ b/src/ProxyClient/ProxyClient.php
@@ -27,5 +27,5 @@ interface ProxyClient
      *
      * @throws ExceptionCollection if any errors occurred during flush
      */
-    public function flush();
+    public function flush(): int;
 }
diff --git a/src/ProxyClient/Symfony.php b/src/ProxyClient/Symfony.php
index 07f5059c4..eacbf733f 100644
--- a/src/ProxyClient/Symfony.php
+++ b/src/ProxyClient/Symfony.php
@@ -17,6 +17,7 @@
 use FOS\HttpCache\ProxyClient\Invalidation\TagCapable;
 use FOS\HttpCache\SymfonyCache\PurgeListener;
 use FOS\HttpCache\SymfonyCache\PurgeTagsListener;
+use Symfony\Component\OptionsResolver\OptionsResolver;
 
 /**
  * Symfony HttpCache invalidator.
@@ -31,14 +32,14 @@ class Symfony extends HttpProxyClient implements PurgeCapable, RefreshCapable, T
 {
     public const HTTP_METHOD_REFRESH = 'GET';
 
-    public function purge($url, array $headers = [])
+    public function purge(string $url, array $headers = []): static
     {
         $this->queueRequest($this->options['purge_method'], $url, $headers);
 
         return $this;
     }
 
-    public function refresh($url, array $headers = [])
+    public function refresh(string $url, array $headers = []): static
     {
         $headers = array_merge($headers, ['Cache-Control' => 'no-cache']);
         $this->queueRequest(self::HTTP_METHOD_REFRESH, $url, $headers);
@@ -46,7 +47,7 @@ public function refresh($url, array $headers = [])
         return $this;
     }
 
-    protected function configureOptions()
+    protected function configureOptions(): OptionsResolver
     {
         $resolver = parent::configureOptions();
         $resolver->setDefaults([
@@ -67,7 +68,7 @@ protected function configureOptions()
         return $resolver;
     }
 
-    public function invalidateTags(array $tags)
+    public function invalidateTags(array $tags): static
     {
         if (!$tags) {
             return $this;
@@ -94,10 +95,8 @@ public function invalidateTags(array $tags)
      *
      * Clearing the cache is implemented with a purge request with a special
      * header to indicate that the whole cache should be removed.
-     *
-     * @return $this
      */
-    public function clear()
+    public function clear(): static
     {
         $this->queueRequest(
             $this->options['purge_method'],
diff --git a/src/ProxyClient/Varnish.php b/src/ProxyClient/Varnish.php
index e85ba7ea4..a4b7137e2 100644
--- a/src/ProxyClient/Varnish.php
+++ b/src/ProxyClient/Varnish.php
@@ -17,6 +17,7 @@
 use FOS\HttpCache\ProxyClient\Invalidation\RefreshCapable;
 use FOS\HttpCache\ProxyClient\Invalidation\TagCapable;
 use Symfony\Component\OptionsResolver\Options;
+use Symfony\Component\OptionsResolver\OptionsResolver;
 
 /**
  * Varnish HTTP cache invalidator.
@@ -60,14 +61,12 @@ class Varnish extends HttpProxyClient implements BanCapable, PurgeCapable, Refre
      *
      * This happens to be the same as TagHeaderFormatter::DEFAULT_HEADER_NAME
      * but does not technically need to be the same.
-     *
-     * @var string
      */
     public const DEFAULT_HTTP_HEADER_CACHE_TAGS = 'X-Cache-Tags';
 
     public const DEFAULT_HTTP_HEADER_CACHE_XKEY = 'xkey-softpurge';
 
-    public function invalidateTags(array $tags)
+    public function invalidateTags(array $tags): static
     {
         if (!$tags) {
             return $this;
@@ -93,7 +92,7 @@ public function invalidateTags(array $tags)
         return $this;
     }
 
-    public function ban(array $headers)
+    public function ban(array $headers): static
     {
         $headers = array_merge(
             $this->options['default_ban_headers'],
@@ -105,7 +104,7 @@ public function ban(array $headers)
         return $this;
     }
 
-    public function banPath($path, $contentType = null, $hosts = null)
+    public function banPath(string $path, ?string $contentType = null, array|string|null $hosts = null): static
     {
         if (is_array($hosts)) {
             if (!count($hosts)) {
@@ -128,14 +127,14 @@ public function banPath($path, $contentType = null, $hosts = null)
         return $this->ban($headers);
     }
 
-    public function purge($url, array $headers = [])
+    public function purge(string $url, array $headers = []): static
     {
         $this->queueRequest(self::HTTP_METHOD_PURGE, $url, $headers);
 
         return $this;
     }
 
-    public function refresh($url, array $headers = [])
+    public function refresh(string $url, array $headers = []): static
     {
         $headers = array_merge($headers, ['Cache-Control' => 'no-cache']);
         $this->queueRequest(self::HTTP_METHOD_REFRESH, $url, $headers);
@@ -143,7 +142,7 @@ public function refresh($url, array $headers = [])
         return $this;
     }
 
-    protected function configureOptions()
+    protected function configureOptions(): OptionsResolver
     {
         $resolver = parent::configureOptions();
         $resolver->setDefaults([
@@ -174,13 +173,19 @@ protected function configureOptions()
         return $resolver;
     }
 
-    private function invalidateByBan(array $tagchunk)
+    /**
+     * @param string[] $tagchunk
+     */
+    private function invalidateByBan(array $tagchunk): void
     {
         $tagExpression = sprintf('(^|,)(%s)(,|$)', implode('|', $tagchunk));
         $this->ban([$this->options['tags_header'] => $tagExpression]);
     }
 
-    private function invalidateByPurgekeys(array $tagchunk)
+    /**
+     * @param string[] $tagchunk
+     */
+    private function invalidateByPurgekeys(array $tagchunk): void
     {
         $this->queueRequest(
             self::HTTP_METHOD_PURGEKEYS,
diff --git a/src/ResponseTagger.php b/src/ResponseTagger.php
index 495a694c7..6b68dadab 100644
--- a/src/ResponseTagger.php
+++ b/src/ResponseTagger.php
@@ -34,20 +34,14 @@
  */
 class ResponseTagger
 {
-    /**
-     * @var array
-     */
-    private $options;
+    private array $options;
 
-    /**
-     * @var TagHeaderFormatter
-     */
-    private $headerFormatter;
+    private TagHeaderFormatter $headerFormatter;
 
     /**
-     * @var array
+     * @var string[]
      */
-    private $tags = [];
+    private array $tags = [];
 
     /**
      * Create the response tagger with a tag header formatter and options.
@@ -77,10 +71,8 @@ public function __construct(array $options = [])
 
     /**
      * Get the HTTP header name that will hold cache tags.
-     *
-     * @return string
      */
-    public function getTagsHeaderName()
+    public function getTagsHeaderName(): string
     {
         return $this->headerFormatter->getTagsHeaderName();
     }
@@ -90,9 +82,9 @@ public function getTagsHeaderName()
      *
      * This concatenates all tags and ensures correct encoding.
      *
-     * @erturn string
+     * @return string|string[]
      */
-    public function getTagsHeaderValue()
+    public function getTagsHeaderValue(): string|array
     {
         return $this->headerFormatter->getTagsHeaderValue($this->tags);
     }
@@ -104,23 +96,21 @@ public function getTagsHeaderValue()
      *
      * @return string[]
      */
-    protected function parseTagsHeaderValue(array|string $headers)
+    protected function parseTagsHeaderValue(array|string $headers): array
     {
         if ($this->headerFormatter instanceof TagHeaderParser) {
             return $this->headerFormatter->parseTagsHeaderValue($headers);
         }
 
-        return array_merge(...array_map(function ($header) {
+        return array_merge(...array_map(static function ($header) {
             return explode(',', $header);
         }, $headers));
     }
 
     /**
      * Check whether the tag handler has any tags to set on the response.
-     *
-     * @return bool
      */
-    public function hasTags()
+    public function hasTags(): bool
     {
         return 0 < count($this->tags);
     }
@@ -132,11 +122,9 @@ public function hasTags()
      *
      * @param string[] $tags List of tags to add
      *
-     * @return $this
-     *
      * @throws InvalidTagException
      */
-    public function addTags(array $tags)
+    public function addTags(array $tags): self
     {
         $filtered = array_filter($tags, 'is_string');
         $filtered = array_filter($filtered, 'strlen');
@@ -166,11 +154,9 @@ public function clear(): void
      *
      * @param ResponseInterface $response Original response
      * @param bool              $replace  Whether to replace the current tags
-     *                                    on the response
-     *
-     * @return ResponseInterface
+     *                                    on the response or add them additionally
      */
-    public function tagResponse(ResponseInterface $response, bool $replace = false)
+    public function tagResponse(ResponseInterface $response, bool $replace = false): ResponseInterface
     {
         if (!$this->hasTags()) {
             return $response;
@@ -179,6 +165,7 @@ public function tagResponse(ResponseInterface $response, bool $replace = false)
         $tagsHeaderValue = $this->getTagsHeaderValue();
         $this->clear();
 
+        // withHeader accepts a single header or an array of multiple headers.
         if ($replace) {
             return $response->withHeader($this->getTagsHeaderName(), $tagsHeaderValue);
         }
diff --git a/src/SymfonyCache/AccessControlledListener.php b/src/SymfonyCache/AccessControlledListener.php
index faa497a48..21e28df18 100644
--- a/src/SymfonyCache/AccessControlledListener.php
+++ b/src/SymfonyCache/AccessControlledListener.php
@@ -59,10 +59,8 @@ public function __construct(array $options = [])
 
     /**
      * Get the options resolver for the constructor arguments.
-     *
-     * @return OptionsResolver
      */
-    protected function getOptionsResolver()
+    protected function getOptionsResolver(): OptionsResolver
     {
         $resolver = new OptionsResolver();
         $resolver->setDefaults([
@@ -75,14 +73,7 @@ protected function getOptionsResolver()
         return $resolver;
     }
 
-    /**
-     * Check whether the request is allowed.
-     *
-     * @param Request $request The request to check
-     *
-     * @return bool Whether access is granted
-     */
-    protected function isRequestAllowed(Request $request)
+    protected function isRequestAllowed(Request $request): bool
     {
         return $this->clientMatcher->matches($request);
     }
diff --git a/src/SymfonyCache/CleanupCacheTagsListener.php b/src/SymfonyCache/CleanupCacheTagsListener.php
index 2de9d5a66..16b65a1fe 100644
--- a/src/SymfonyCache/CleanupCacheTagsListener.php
+++ b/src/SymfonyCache/CleanupCacheTagsListener.php
@@ -22,20 +22,17 @@
  */
 class CleanupCacheTagsListener implements EventSubscriberInterface
 {
-    /**
-     * @var string
-     */
-    private $tagsHeader;
+    private string $tagsHeader;
 
     /**
      * @param string $tagsHeader The header that is used for cache tags
      */
-    public function __construct($tagsHeader = TagHeaderFormatter::DEFAULT_HEADER_NAME)
+    public function __construct(string $tagsHeader = TagHeaderFormatter::DEFAULT_HEADER_NAME)
     {
         $this->tagsHeader = $tagsHeader;
     }
 
-    public function removeTagsHeader(CacheEvent $e)
+    public function removeTagsHeader(CacheEvent $e): void
     {
         if (null === $response = $e->getResponse()) {
             return;
diff --git a/src/SymfonyCache/CustomTtlListener.php b/src/SymfonyCache/CustomTtlListener.php
index 850fe1845..8bad52a5d 100644
--- a/src/SymfonyCache/CustomTtlListener.php
+++ b/src/SymfonyCache/CustomTtlListener.php
@@ -23,20 +23,12 @@
  */
 class CustomTtlListener implements EventSubscriberInterface
 {
-    /**
-     * @var string
-     */
-    private $ttlHeader;
+    private string $ttlHeader;
 
-    /**
-     * @var bool
-     */
-    private $keepTtlHeader;
+    private bool $keepTtlHeader;
 
     /**
      * Header used for backing up the s-maxage.
-     *
-     * @var string
      */
     public const SMAXAGE_BACKUP = 'FOS-Smaxage-Backup';
 
@@ -44,7 +36,7 @@ class CustomTtlListener implements EventSubscriberInterface
      * @param string $ttlHeader     The header name that is used to specify the time to live
      * @param bool   $keepTtlHeader Keep the custom TTL header on the response for later usage (e.g. debugging)
      */
-    public function __construct($ttlHeader = 'X-Reverse-Proxy-TTL', $keepTtlHeader = false)
+    public function __construct(string $ttlHeader = 'X-Reverse-Proxy-TTL', bool $keepTtlHeader = false)
     {
         $this->ttlHeader = $ttlHeader;
         $this->keepTtlHeader = $keepTtlHeader;
@@ -56,9 +48,12 @@ public function __construct($ttlHeader = 'X-Reverse-Proxy-TTL', $keepTtlHeader =
      * If there is such a header, the original s_maxage is backed up to the
      * static::SMAXAGE_BACKUP header.
      */
-    public function useCustomTtl(CacheEvent $e)
+    public function useCustomTtl(CacheEvent $e): void
     {
         $response = $e->getResponse();
+        if (!$response) {
+            return;
+        }
         if (!$response->headers->has($this->ttlHeader)) {
             return;
         }
@@ -73,9 +68,12 @@ public function useCustomTtl(CacheEvent $e)
     /**
      * Remove the custom TTL header and restore s_maxage from the backup.
      */
-    public function cleanResponse(CacheEvent $e)
+    public function cleanResponse(CacheEvent $e): void
     {
         $response = $e->getResponse();
+        if (!$response) {
+            return;
+        }
         if (!$response->headers->has($this->ttlHeader)
             && !$response->headers->has(static::SMAXAGE_BACKUP)
         ) {
diff --git a/src/SymfonyCache/DebugListener.php b/src/SymfonyCache/DebugListener.php
index b3738e88d..0294f6409 100644
--- a/src/SymfonyCache/DebugListener.php
+++ b/src/SymfonyCache/DebugListener.php
@@ -35,13 +35,16 @@ public static function getSubscribedEvents(): array
      * For this header to be present, the HttpCache must be created with the
      * debug option set to true.
      */
-    public function handleDebug(CacheEvent $event)
+    public function handleDebug(CacheEvent $event): void
     {
         $response = $event->getResponse();
+        if (!$response) {
+            return;
+        }
         if ($response->headers->has('X-Symfony-Cache')) {
-            if (false !== strpos($response->headers->get('X-Symfony-Cache'), 'miss')) {
+            if (str_contains($response->headers->get('X-Symfony-Cache'), 'miss')) {
                 $state = 'MISS';
-            } elseif (false !== strpos($response->headers->get('X-Symfony-Cache'), 'fresh')) {
+            } elseif (str_contains($response->headers->get('X-Symfony-Cache'), 'fresh')) {
                 $state = 'HIT';
             } else {
                 $state = 'UNDETERMINED';
diff --git a/src/SymfonyCache/EventDispatchingHttpCache.php b/src/SymfonyCache/EventDispatchingHttpCache.php
index 1be403a1b..36a3c4ab9 100644
--- a/src/SymfonyCache/EventDispatchingHttpCache.php
+++ b/src/SymfonyCache/EventDispatchingHttpCache.php
@@ -66,7 +66,7 @@ public function addSubscriber(EventSubscriberInterface $subscriber): void
      *
      * @see EventDispatcherInterface::addListener
      */
-    public function addListener($eventName, $listener, $priority = 0): void
+    public function addListener(string $eventName, callable $listener, int $priority = 0): void
     {
         $this->getEventDispatcher()->addListener($eventName, $listener, $priority);
     }
@@ -76,7 +76,7 @@ public function addListener($eventName, $listener, $priority = 0): void
      *
      * Adding the Events::PRE_HANDLE and Events::POST_HANDLE events.
      */
-    public function handle(Request $request, $type = HttpKernelInterface::MAIN_REQUEST, $catch = true): Response
+    public function handle(Request $request, int $type = HttpKernelInterface::MAIN_REQUEST, bool $catch = true): Response
     {
         // trigger loading the CacheEvent to avoid fatal error when HttpKernel::loadClassCache is used.
         class_exists(CacheEvent::class);
@@ -107,7 +107,7 @@ protected function store(Request $request, Response $response): void
      *
      * Adding the Events::PRE_INVALIDATE event.
      */
-    protected function invalidate(Request $request, $catch = false): Response
+    protected function invalidate(Request $request, bool $catch = false): Response
     {
         if ($response = $this->dispatch(Events::PRE_INVALIDATE, $request)) {
             return $response;
diff --git a/src/SymfonyCache/HttpCacheAware.php b/src/SymfonyCache/HttpCacheAware.php
index b736678dc..17a2c3511 100644
--- a/src/SymfonyCache/HttpCacheAware.php
+++ b/src/SymfonyCache/HttpCacheAware.php
@@ -18,20 +18,14 @@
  */
 trait HttpCacheAware
 {
-    /**
-     * @var HttpKernelInterface|null
-     */
-    private $httpCache;
+    private ?HttpKernelInterface $httpCache;
 
-    /**
-     * @return HttpKernelInterface|null
-     */
-    public function getHttpCache()
+    public function getHttpCache(): ?HttpKernelInterface
     {
         return $this->httpCache;
     }
 
-    public function setHttpCache(HttpKernelInterface $httpCache)
+    public function setHttpCache(HttpKernelInterface $httpCache): void
     {
         $this->httpCache = $httpCache;
     }
diff --git a/src/SymfonyCache/HttpCacheProvider.php b/src/SymfonyCache/HttpCacheProvider.php
index 055b4a395..9dbf14d64 100644
--- a/src/SymfonyCache/HttpCacheProvider.php
+++ b/src/SymfonyCache/HttpCacheProvider.php
@@ -15,8 +15,5 @@
 
 interface HttpCacheProvider
 {
-    /**
-     * @return HttpKernelInterface|null
-     */
-    public function getHttpCache();
+    public function getHttpCache(): ?HttpKernelInterface;
 }
diff --git a/src/SymfonyCache/KernelDispatcher.php b/src/SymfonyCache/KernelDispatcher.php
index 789adf24c..c7a23a47a 100644
--- a/src/SymfonyCache/KernelDispatcher.php
+++ b/src/SymfonyCache/KernelDispatcher.php
@@ -44,7 +44,7 @@ public function __construct(HttpCacheProvider $httpCacheProvider)
         $this->httpCacheProvider = $httpCacheProvider;
     }
 
-    public function invalidate(RequestInterface $invalidationRequest, $validateHost = true): void
+    public function invalidate(RequestInterface $invalidationRequest, bool $validateHost = true): void
     {
         $request = Request::create(
             $invalidationRequest->getUri(),
diff --git a/src/SymfonyCache/PurgeListener.php b/src/SymfonyCache/PurgeListener.php
index d146ae3ce..7c819695b 100644
--- a/src/SymfonyCache/PurgeListener.php
+++ b/src/SymfonyCache/PurgeListener.php
@@ -29,17 +29,13 @@ class PurgeListener extends AccessControlledListener
 
     /**
      * The purge method to use.
-     *
-     * @var string
      */
-    private $purgeMethod;
+    private string $purgeMethod;
 
     /**
      * The clear cache header to use.
-     *
-     * @var string
      */
-    private $clearCacheHeader;
+    private string $clearCacheHeader;
 
     /**
      * When creating the purge listener, you can configure an additional option.
@@ -73,7 +69,7 @@ public static function getSubscribedEvents(): array
      *
      * Prevents access when the request comes from a non-authorized client.
      */
-    public function handlePurge(CacheEvent $event)
+    public function handlePurge(CacheEvent $event): void
     {
         $request = $event->getRequest();
         if ($this->purgeMethod !== $request->getMethod()) {
@@ -117,10 +113,8 @@ public function handlePurge(CacheEvent $event)
 
     /**
      * Add the purge_method option.
-     *
-     * @return OptionsResolver
      */
-    protected function getOptionsResolver()
+    protected function getOptionsResolver(): OptionsResolver
     {
         $resolver = parent::getOptionsResolver();
         $resolver->setDefault('purge_method', static::DEFAULT_PURGE_METHOD);
diff --git a/src/SymfonyCache/PurgeTagsListener.php b/src/SymfonyCache/PurgeTagsListener.php
index 90649dfad..acf863c8e 100644
--- a/src/SymfonyCache/PurgeTagsListener.php
+++ b/src/SymfonyCache/PurgeTagsListener.php
@@ -30,22 +30,15 @@ class PurgeTagsListener extends AccessControlledListener
 
     /**
      * The purge tags method to use.
-     *
-     * @var string
      */
-    private $tagsMethod;
+    private string $tagsMethod;
 
     /**
      * The purge tags header to use.
-     *
-     * @var string
      */
-    private $tagsHeader;
+    private string $tagsHeader;
 
-    /**
-     * @var TagHeaderParser
-     */
-    private $tagsParser;
+    private TagHeaderParser $tagsParser;
 
     /**
      * When creating the purge listener, you can configure an additional option.
@@ -85,7 +78,7 @@ public static function getSubscribedEvents(): array
      *
      * Prevents access when the request comes from a non-authorized client.
      */
-    public function handlePurgeTags(CacheEvent $event)
+    public function handlePurgeTags(CacheEvent $event): void
     {
         $request = $event->getRequest();
         if ($this->tagsMethod !== $request->getMethod()) {
@@ -141,10 +134,8 @@ public function handlePurgeTags(CacheEvent $event)
 
     /**
      * Add the purge_method option.
-     *
-     * @return OptionsResolver
      */
-    protected function getOptionsResolver()
+    protected function getOptionsResolver(): OptionsResolver
     {
         $resolver = parent::getOptionsResolver();
         $resolver->setDefaults([
diff --git a/src/SymfonyCache/RefreshListener.php b/src/SymfonyCache/RefreshListener.php
index 5807355a3..995638e3b 100644
--- a/src/SymfonyCache/RefreshListener.php
+++ b/src/SymfonyCache/RefreshListener.php
@@ -36,7 +36,7 @@ public static function getSubscribedEvents(): array
      * When the request comes from a non-authorized client, ignore refresh to
      * let normal lookup happen.
      */
-    public function handleRefresh(CacheEvent $event)
+    public function handleRefresh(CacheEvent $event): void
     {
         $request = $event->getRequest();
         // BC - we can drop this check when we only support Symfony 3.1 and newer
diff --git a/src/SymfonyCache/UserContextListener.php b/src/SymfonyCache/UserContextListener.php
index c5c46cc96..37e6b70af 100644
--- a/src/SymfonyCache/UserContextListener.php
+++ b/src/SymfonyCache/UserContextListener.php
@@ -27,17 +27,13 @@ class UserContextListener implements EventSubscriberInterface
 {
     /**
      * The options configured in the constructor argument or default values.
-     *
-     * @var array
      */
-    private $options;
+    private array $options;
 
     /**
      * Generated user hash.
-     *
-     * @var string
      */
-    private $userHash;
+    private string $userHash;
 
     /**
      * When creating this listener, you can configure a number of options.
@@ -193,12 +189,10 @@ private function isAnonymous(Request $request): bool
 
     /**
      * Checks if passed string can be considered as a session name, such as would be used in cookies.
-     *
-     * @param string $name
      */
-    private function isSessionName($name): bool
+    private function isSessionName(string $name): bool
     {
-        return 0 === strpos($name, $this->options['session_name_prefix']);
+        return str_starts_with($name, $this->options['session_name_prefix']);
     }
 
     /**
diff --git a/src/TagHeaderFormatter/CommaSeparatedTagHeaderFormatter.php b/src/TagHeaderFormatter/CommaSeparatedTagHeaderFormatter.php
index 36ddc5008..cb34c1fb6 100644
--- a/src/TagHeaderFormatter/CommaSeparatedTagHeaderFormatter.php
+++ b/src/TagHeaderFormatter/CommaSeparatedTagHeaderFormatter.php
@@ -18,37 +18,27 @@
  */
 class CommaSeparatedTagHeaderFormatter implements TagHeaderFormatter, TagHeaderParser
 {
-    /**
-     * @var string
-     */
-    private $headerName;
-
-    /**
-     * @var string
-     */
-    private $glue;
-
-    /**
-     * @param string $headerName
-     * @param string $glue       Separator character for the tag header
-     */
-    public function __construct($headerName = TagHeaderFormatter::DEFAULT_HEADER_NAME, $glue = ',')
+    private string $headerName;
+
+    private string $glue;
+
+    public function __construct(string $headerName = TagHeaderFormatter::DEFAULT_HEADER_NAME, string $glue = ',')
     {
         $this->headerName = $headerName;
         $this->glue = $glue;
     }
 
-    public function getTagsHeaderName()
+    public function getTagsHeaderName(): string
     {
         return $this->headerName;
     }
 
-    public function getTagsHeaderValue(array $tags)
+    public function getTagsHeaderValue(array $tags): array|string
     {
         return implode($this->glue, $tags);
     }
 
-    public function parseTagsHeaderValue($tags): array
+    public function parseTagsHeaderValue(array|string $tags): array
     {
         if (is_string($tags)) {
             $tags = [$tags];
diff --git a/src/TagHeaderFormatter/MaxHeaderValueLengthFormatter.php b/src/TagHeaderFormatter/MaxHeaderValueLengthFormatter.php
index aa051697d..5895f6b66 100644
--- a/src/TagHeaderFormatter/MaxHeaderValueLengthFormatter.php
+++ b/src/TagHeaderFormatter/MaxHeaderValueLengthFormatter.php
@@ -23,43 +23,35 @@
  */
 class MaxHeaderValueLengthFormatter implements TagHeaderFormatter, TagHeaderParser
 {
-    /**
-     * @var TagHeaderFormatter
-     */
-    private $inner;
+    private TagHeaderFormatter $inner;
 
-    /**
-     * @var int
-     */
-    private $maxHeaderValueLength;
+    private int $maxHeaderValueLength;
 
     /**
      * The default value of the maximum header length is 4096 because most
      * servers limit header values to 4kb.
      * HTTP messages cannot carry characters outside the ISO-8859-1 standard so they all
      * use up just one byte.
-     *
-     * @param int $maxHeaderValueLength
      */
-    public function __construct(TagHeaderFormatter $inner, $maxHeaderValueLength = 4096)
+    public function __construct(TagHeaderFormatter $inner, int $maxHeaderValueLength = 4096)
     {
         $this->inner = $inner;
         $this->maxHeaderValueLength = $maxHeaderValueLength;
     }
 
-    public function getTagsHeaderName()
+    public function getTagsHeaderName(): string
     {
         return $this->inner->getTagsHeaderName();
     }
 
-    public function getTagsHeaderValue(array $tags)
+    public function getTagsHeaderValue(array $tags): array|string
     {
         $values = (array) $this->inner->getTagsHeaderValue($tags);
         $newValues = [[]];
 
         foreach ($values as $value) {
             if ($this->isHeaderTooLong($value)) {
-                list($firstTags, $secondTags) = $this->splitTagsInHalves($tags);
+                [$firstTags, $secondTags] = $this->splitTagsInHalves($tags);
 
                 $newValues[] = (array) $this->getTagsHeaderValue($firstTags);
                 $newValues[] = (array) $this->getTagsHeaderValue($secondTags);
@@ -77,7 +69,7 @@ public function getTagsHeaderValue(array $tags)
         return $newValues;
     }
 
-    public function parseTagsHeaderValue($tags): array
+    public function parseTagsHeaderValue(array|string $tags): array
     {
         if ($this->inner instanceof TagHeaderParser) {
             return $this->inner->parseTagsHeaderValue($tags);
@@ -86,12 +78,7 @@ public function parseTagsHeaderValue($tags): array
         throw new \BadMethodCallException('The inner formatter does not implement '.TagHeaderParser::class);
     }
 
-    /**
-     * @param string $value
-     *
-     * @return bool
-     */
-    private function isHeaderTooLong($value)
+    private function isHeaderTooLong(string $value): bool
     {
         return mb_strlen($value) > $this->maxHeaderValueLength;
     }
@@ -99,11 +86,11 @@ private function isHeaderTooLong($value)
     /**
      * Split an array of tags in two more or less equal sized arrays.
      *
-     * @return array
+     * @return string[][]
      *
      * @throws InvalidTagException
      */
-    private function splitTagsInHalves(array $tags)
+    private function splitTagsInHalves(array $tags): array
     {
         if (1 === count($tags)) {
             throw new InvalidTagException(sprintf(
diff --git a/src/TagHeaderFormatter/TagHeaderFormatter.php b/src/TagHeaderFormatter/TagHeaderFormatter.php
index 83fe3be00..d972f9af8 100644
--- a/src/TagHeaderFormatter/TagHeaderFormatter.php
+++ b/src/TagHeaderFormatter/TagHeaderFormatter.php
@@ -27,10 +27,8 @@ interface TagHeaderFormatter
 
     /**
      * Get the HTTP header name that will hold cache tags.
-     *
-     * @return string
      */
-    public function getTagsHeaderName();
+    public function getTagsHeaderName(): string;
 
     /**
      * Get the value for the HTTP tag header.
@@ -39,5 +37,5 @@ public function getTagsHeaderName();
      *
      * @return string|string[]
      */
-    public function getTagsHeaderValue(array $tags);
+    public function getTagsHeaderValue(array $tags): array|string;
 }
diff --git a/src/TagHeaderFormatter/TagHeaderParser.php b/src/TagHeaderFormatter/TagHeaderParser.php
index c176cf981..6d1ecdc13 100644
--- a/src/TagHeaderFormatter/TagHeaderParser.php
+++ b/src/TagHeaderFormatter/TagHeaderParser.php
@@ -25,5 +25,5 @@ interface TagHeaderParser
      *
      * @return string[]
      */
-    public function parseTagsHeaderValue($tags): array;
+    public function parseTagsHeaderValue(array|string $tags): array;
 }
diff --git a/src/Test/CacheAssertions.php b/src/Test/CacheAssertions.php
index 52c45584b..c5eb8d109 100644
--- a/src/Test/CacheAssertions.php
+++ b/src/Test/CacheAssertions.php
@@ -33,7 +33,7 @@ trait CacheAssertions
      *
      * @param string $message Test failure message (optional)
      */
-    public function assertMiss(ResponseInterface $response, $message = '')
+    public function assertMiss(ResponseInterface $response, string $message = ''): void
     {
         TestCase::assertThat($response, self::isCacheMiss(), $message);
     }
@@ -43,17 +43,17 @@ public function assertMiss(ResponseInterface $response, $message = '')
      *
      * @param string $message Test failure message (optional)
      */
-    public function assertHit(ResponseInterface $response, $message = '')
+    public function assertHit(ResponseInterface $response, string $message = ''): void
     {
         TestCase::assertThat($response, self::isCacheHit(), $message);
     }
 
-    public static function isCacheHit()
+    public static function isCacheHit(): IsCacheHitConstraint
     {
         return new IsCacheHitConstraint();
     }
 
-    public static function isCacheMiss()
+    public static function isCacheMiss(): IsCacheMissConstraint
     {
         return new IsCacheMissConstraint();
     }
diff --git a/src/Test/EventDispatchingHttpCacheTestCase.php b/src/Test/EventDispatchingHttpCacheTestCase.php
index 6c4f5ab64..c59e79990 100644
--- a/src/Test/EventDispatchingHttpCacheTestCase.php
+++ b/src/Test/EventDispatchingHttpCacheTestCase.php
@@ -32,18 +32,16 @@ abstract class EventDispatchingHttpCacheTestCase extends TestCase
     /**
      * Specify the CacheInvalidationInterface HttpCache class to test.
      *
-     * @return string Fully qualified class name of the AppCache
+     * @return class-string Fully qualified class name of the AppCache
      */
-    abstract protected function getCacheClass();
+    abstract protected function getCacheClass(): string;
 
     /**
      * Create a partial mock of the HttpCache to only test some methods.
      *
-     * @param array $mockedMethods List of methods to mock
-     *
-     * @return CacheInvalidation|EventDispatchingHttpCache|MockObject
+     * @param string[] $mockedMethods List of methods to mock
      */
-    protected function getHttpCachePartialMock(?array $mockedMethods = null)
+    protected function getHttpCachePartialMock(?array $mockedMethods = null): MockObject|CacheInvalidation|EventDispatchingHttpCache
     {
         $mock = $this
             ->getMockBuilder($this->getCacheClass())
@@ -70,11 +68,9 @@ protected function getHttpCachePartialMock(?array $mockedMethods = null)
 
         $refHttpCache = new \ReflectionClass(HttpCache::class);
         $refOptions = $refHttpCache->getProperty('options');
-        $refOptions->setAccessible(true);
         $refOptions->setValue($mock, $options);
 
         $surrogate = $refHttpCache->getProperty('surrogate');
-        $surrogate->setAccessible(true);
         $surrogate->setValue($mock, null);
 
         return $mock;
@@ -83,7 +79,7 @@ protected function getHttpCachePartialMock(?array $mockedMethods = null)
     /**
      * Set the store property on a HttpCache to a StoreInterface expecting one write with request and response.
      */
-    protected function setStoreMock(CacheInvalidation $httpCache, Request $request, Response $response)
+    protected function setStoreMock(CacheInvalidation $httpCache, Request $request, Response $response): void
     {
         $store = $this->createMock(StoreInterface::class);
         $store
@@ -93,14 +89,13 @@ protected function setStoreMock(CacheInvalidation $httpCache, Request $request,
         ;
         $refHttpCache = new \ReflectionClass(HttpCache::class);
         $refStore = $refHttpCache->getProperty('store');
-        $refStore->setAccessible(true);
         $refStore->setValue($httpCache, $store);
     }
 
     /**
      * Assert that preHandle and postHandle are called.
      */
-    public function testHandleCalled()
+    public function testHandleCalled(): void
     {
         $catch = true;
         $request = Request::create('/foo', 'GET');
@@ -176,7 +171,7 @@ public function testPostHandleReturn(): void
      *
      * @depends testHandleCalled
      */
-    public function testPostHandleAfterPreHandle()
+    public function testPostHandleAfterPreHandle(): void
     {
         $catch = true;
         $request = Request::create('/foo', 'GET');
@@ -201,7 +196,7 @@ public function testPostHandleAfterPreHandle()
     /**
      * Assert that preStore is called.
      */
-    public function testPreStoreCalled()
+    public function testPreStoreCalled(): void
     {
         $request = Request::create('/foo', 'GET');
         $response = new Response();
@@ -214,7 +209,6 @@ public function testPreStoreCalled()
 
         $refHttpCache = new \ReflectionObject($httpCache);
         $method = $refHttpCache->getMethod('store');
-        $method->setAccessible(true);
         $method->invokeArgs($httpCache, [$request, $response]);
         $this->assertEquals(1, $testListener->preStoreCalls);
     }
@@ -222,7 +216,7 @@ public function testPreStoreCalled()
     /**
      * Assert that preStore response is used when provided.
      */
-    public function testPreStoreResponse()
+    public function testPreStoreResponse(): void
     {
         $request = Request::create('/foo', 'GET');
         $regularResponse = new Response();
@@ -237,7 +231,6 @@ public function testPreStoreResponse()
 
         $refHttpCache = new \ReflectionObject($httpCache);
         $method = $refHttpCache->getMethod('store');
-        $method->setAccessible(true);
         $method->invokeArgs($httpCache, [$request, $regularResponse]);
         $this->assertEquals(1, $testListener->preStoreCalls);
     }
@@ -245,7 +238,7 @@ public function testPreStoreResponse()
     /**
      * Assert that preInvalidate is called.
      */
-    public function testPreInvalidateCalled()
+    public function testPreInvalidateCalled(): void
     {
         $catch = true;
         $request = Request::create('/foo', 'GET');
@@ -261,7 +254,6 @@ public function testPreInvalidateCalled()
         ;
         $refHttpCache = new \ReflectionObject($httpCache);
         $method = $refHttpCache->getMethod('invalidate');
-        $method->setAccessible(true);
 
         $this->assertSame($response, $method->invokeArgs($httpCache, [$request, $catch]));
         $this->assertEquals(1, $testListener->preInvalidateCalls);
@@ -288,7 +280,6 @@ public function testPreInvalidateReturnEarly(): void
         ;
         $refHttpCache = new \ReflectionObject($httpCache);
         $method = $refHttpCache->getMethod('invalidate');
-        $method->setAccessible(true);
 
         $this->assertSame($response, $method->invokeArgs($httpCache, [$request, $catch]));
         $this->assertEquals(1, $testListener->preInvalidateCalls);
diff --git a/src/Test/HttpCaller.php b/src/Test/HttpCaller.php
index a9de5bf7d..d705d712a 100644
--- a/src/Test/HttpCaller.php
+++ b/src/Test/HttpCaller.php
@@ -20,23 +20,18 @@ trait HttpCaller
 {
     /**
      * HTTP client for requests to the application.
-     *
-     * @var HttpClient
      */
-    private $httpClient;
+    private HttpClient $httpClient;
 
     /**
      * Call a HTTP resource from your test.
      *
-     * @param string $uri     HTTP URI, domain and port are added from the embedding class if not specified
-     * @param array  $headers HTTP headers
-     * @param string $method  HTTP method
-     *
-     * @return ResponseInterface
+     * @param string                $uri     HTTP URI, domain and port are added from the embedding class if not specified
+     * @param array<string, string> $headers HTTP headers
      */
-    protected function getResponse($uri, array $headers = [], $method = 'GET')
+    protected function getResponse(string $uri, array $headers = [], string $method = 'GET'): ResponseInterface
     {
-        if (!$this->httpClient) {
+        if (!isset($this->httpClient)) {
             $this->httpClient = new HttpClient($this->getHostName(), $this->getCachingProxyPort());
         }
 
@@ -45,15 +40,11 @@ protected function getResponse($uri, array $headers = [], $method = 'GET')
 
     /**
      * Get the default host name to use.
-     *
-     * @return string
      */
-    abstract protected function getHostName();
+    abstract protected function getHostName(): string;
 
     /**
      * Get the default port to use.
-     *
-     * @return string
      */
-    abstract protected function getCachingProxyPort();
+    abstract protected function getCachingProxyPort(): int;
 }
diff --git a/src/Test/HttpClient.php b/src/Test/HttpClient.php
index 3b02ec4f6..7a280c374 100644
--- a/src/Test/HttpClient.php
+++ b/src/Test/HttpClient.php
@@ -26,26 +26,18 @@ class HttpClient
 {
     /**
      * HTTP client for requests to the application.
-     *
-     * @var PhpHttpClient
      */
-    private $httpClient;
+    private PhpHttpClient $httpClient;
 
-    /**
-     * @var string
-     */
-    private $hostname;
+    private string $hostname;
 
-    /**
-     * @var string
-     */
-    private $port;
+    private string $port;
 
     /**
      * @param string $hostname Default hostname if not specified in the URL
      * @param string $port     Default port if not specified in the URL
      */
-    public function __construct($hostname, $port)
+    public function __construct(string $hostname, string $port)
     {
         $this->hostname = $hostname;
         $this->port = $port;
@@ -57,10 +49,8 @@ public function __construct($hostname, $port)
      * @param string $uri     HTTP URI
      * @param array  $headers HTTP headers
      * @param string $method  HTTP method
-     *
-     * @return ResponseInterface
      */
-    public function getResponse($uri, array $headers, $method)
+    public function getResponse(string $uri, array $headers, string $method): ResponseInterface
     {
         $request = $this->createRequest($method, $uri, $headers);
 
@@ -69,10 +59,8 @@ public function getResponse($uri, array $headers, $method)
 
     /**
      * Send PSR HTTP request to your application.
-     *
-     * @return ResponseInterface
      */
-    public function sendRequest(RequestInterface $request)
+    public function sendRequest(RequestInterface $request): ResponseInterface
     {
         // Close connections to make sure invalidation (PURGE/BAN) requests will
         // not interfere with content (GET) requests.
@@ -83,12 +71,10 @@ public function sendRequest(RequestInterface $request)
 
     /**
      * Get HTTP client for your application.
-     *
-     * @return PhpHttpClient
      */
-    private function getHttpClient()
+    private function getHttpClient(): PhpHttpClient
     {
-        if (null === $this->httpClient) {
+        if (!isset($this->httpClient)) {
             $this->httpClient = HttpClientDiscovery::find();
         }
 
@@ -96,17 +82,11 @@ private function getHttpClient()
     }
 
     /**
-     * Create a request.
-     *
-     * @param string $method
-     * @param string $uri
-     * @param array  $headers
-     *
-     * @return RequestInterface
+     * @param array<string, string> $headers
      *
      * @throws \Exception
      */
-    private function createRequest($method, $uri, $headers)
+    private function createRequest(string $method, string $uri, array $headers): RequestInterface
     {
         $uri = $this->createUri($uri);
         if ('' === $uri->getHost()) {
@@ -131,12 +111,8 @@ private function createRequest($method, $uri, $headers)
 
     /**
      * Create PSR-7 URI object from URI string.
-     *
-     * @param string $uriString
-     *
-     * @return UriInterface
      */
-    private function createUri($uriString)
+    private function createUri(string $uriString): UriInterface
     {
         return UriFactoryDiscovery::find()->createUri($uriString);
     }
diff --git a/src/Test/NginxTest.php b/src/Test/NginxTest.php
index 64a3ea399..563dd6ec8 100644
--- a/src/Test/NginxTest.php
+++ b/src/Test/NginxTest.php
@@ -41,15 +41,8 @@
  */
 trait NginxTest
 {
-    /**
-     * @var Nginx
-     */
-    protected $proxyClient;
-
-    /**
-     * @var NginxProxy
-     */
-    protected $proxy;
+    protected Nginx $proxyClient;
+    protected NginxProxy $proxy;
 
     protected function setUp(): void
     {
@@ -68,7 +61,7 @@ protected function tearDown(): void
      *
      * @throws \Exception
      */
-    protected function getConfigFile()
+    protected function getConfigFile(): string
     {
         // @codeCoverageIgnoreStart
         if (!defined('NGINX_FILE')) {
@@ -85,20 +78,16 @@ protected function getConfigFile()
 
     /**
      * Defaults to "nginx".
-     *
-     * @return string
      */
-    protected function getBinary()
+    protected function getBinary(): ?string
     {
         return defined('NGINX_BINARY') ? NGINX_BINARY : null;
     }
 
     /**
      * Defaults to 8088.
-     *
-     * @return int
      */
-    protected function getCachingProxyPort()
+    protected function getCachingProxyPort(): int
     {
         return defined('NGINX_PORT') ? NGINX_PORT : 8088;
     }
@@ -106,7 +95,7 @@ protected function getCachingProxyPort()
     /**
      * Get NGINX cache directory.
      */
-    protected function getCacheDir()
+    protected function getCacheDir(): ?string
     {
         return defined('NGINX_CACHE_PATH') ? NGINX_CACHE_PATH : null;
     }
@@ -114,11 +103,9 @@ protected function getCacheDir()
     /**
      * Get the hostname where your application can be reached.
      *
-     * @return string
-     *
      * @throws \Exception
      */
-    protected function getHostName()
+    protected function getHostName(): string
     {
         // @codeCoverageIgnoreStart
         if (!defined('WEB_SERVER_HOSTNAME')) {
@@ -131,12 +118,9 @@ protected function getHostName()
         return WEB_SERVER_HOSTNAME;
     }
 
-    /**
-     * @return NginxProxy
-     */
-    protected function getProxy()
+    protected function getProxy(): NginxProxy
     {
-        if (null === $this->proxy) {
+        if (!isset($this->proxy)) {
             $this->proxy = new NginxProxy($this->getConfigFile());
             $this->proxy->setPort($this->getCachingProxyPort());
 
@@ -156,12 +140,10 @@ protected function getProxy()
      * Get proxy client.
      *
      * @param string $purgeLocation Optional purgeLocation
-     *
-     * @return Nginx
      */
-    protected function getProxyClient($purgeLocation = '')
+    protected function getProxyClient(string $purgeLocation = ''): Nginx
     {
-        if (null === $this->proxyClient) {
+        if (!isset($this->proxyClient)) {
             $httpDispatcher = new HttpDispatcher(
                 ['http://127.0.0.1:'.$this->getCachingProxyPort()],
                 $this->getHostName().':'.$this->getCachingProxyPort()
diff --git a/src/Test/PHPUnit/AbstractCacheConstraintTrait.php b/src/Test/PHPUnit/AbstractCacheConstraintTrait.php
index 0d6597213..db18ef45b 100644
--- a/src/Test/PHPUnit/AbstractCacheConstraintTrait.php
+++ b/src/Test/PHPUnit/AbstractCacheConstraintTrait.php
@@ -19,31 +19,21 @@
  */
 trait AbstractCacheConstraintTrait
 {
-    protected $header = 'X-Cache';
+    protected string $header;
 
-    /**
-     * Constructor.
-     *
-     * @param string $header Cache debug header; defaults to X-Cache-Debug
-     */
-    public function __construct($header = null)
+    public function __construct(string $header = 'X-Cache')
     {
-        if ($header) {
-            $this->header = $header;
-        }
+        $this->header = $header;
 
         if (version_compare(Version::id(), '8.0.0', '<')) {
             parent::__construct();
         }
     }
 
-    /**
-     * @param ResponseInterface $other The guzzle response object
-     */
     public function matches($other): bool
     {
         if (!$other instanceof ResponseInterface) {
-            throw new \RuntimeException(sprintf('Expected a GuzzleHttp\Psr7\Response but got %s', get_class($other)));
+            throw new \InvalidArgumentException('compare must compare with '.ResponseInterface::class.' got '.get_debug_type($other));
         }
         if (!$other->hasHeader($this->header)) {
             $message = sprintf(
@@ -70,7 +60,7 @@ public function matches($other): bool
             throw new \RuntimeException($message);
         }
 
-        return false !== strpos((string) $other->getHeaderLine($this->header), $this->getValue());
+        return str_contains($other->getHeaderLine($this->header), $this->getValue());
     }
 
     public function failureDescription($other): string
diff --git a/src/Test/PHPUnit/IsCacheHitConstraint.php b/src/Test/PHPUnit/IsCacheHitConstraint.php
index 13d369367..1c54b3906 100644
--- a/src/Test/PHPUnit/IsCacheHitConstraint.php
+++ b/src/Test/PHPUnit/IsCacheHitConstraint.php
@@ -18,7 +18,7 @@ public function toString(): string
         return 'is a cache hit';
     }
 
-    public function getValue()
+    public function getValue(): string
     {
         return 'HIT';
     }
diff --git a/src/Test/PHPUnit/IsCacheMissConstraint.php b/src/Test/PHPUnit/IsCacheMissConstraint.php
index 52e04b25f..60149125f 100644
--- a/src/Test/PHPUnit/IsCacheMissConstraint.php
+++ b/src/Test/PHPUnit/IsCacheMissConstraint.php
@@ -18,7 +18,7 @@ public function toString(): string
         return 'is a cache miss';
     }
 
-    public function getValue()
+    public function getValue(): string
     {
         return 'MISS';
     }
diff --git a/src/Test/Proxy/AbstractProxy.php b/src/Test/Proxy/AbstractProxy.php
index 174458df1..3b0296714 100644
--- a/src/Test/Proxy/AbstractProxy.php
+++ b/src/Test/Proxy/AbstractProxy.php
@@ -15,24 +15,22 @@
 
 abstract class AbstractProxy implements ProxyInterface
 {
-    protected $port;
+    protected int $port;
 
-    protected $binary;
+    protected string $binary;
 
-    protected $configFile;
+    protected string $configFile;
 
-    protected $ip = '127.0.0.1';
+    protected string $ip = '127.0.0.1';
 
     /**
      * Wait for caching proxy to be started up and reachable.
      *
-     * @param string $ip
-     * @param int    $port
-     * @param int    $timeout Timeout in milliseconds
+     * @param int $timeout Timeout in milliseconds
      *
      * @throws \RuntimeException If proxy is not reachable within timeout
      */
-    protected function waitFor($ip, $port, $timeout)
+    protected function waitFor(string $ip, int $port, int $timeout): void
     {
         if (!$this->wait(
             $timeout,
@@ -53,13 +51,11 @@ function () use ($ip, $port) {
     /**
      * Wait for caching proxy to be started up and reachable.
      *
-     * @param string $ip
-     * @param int    $port
-     * @param int    $timeout Timeout in milliseconds
+     * @param int $timeout Timeout in milliseconds
      *
      * @throws \RuntimeException If proxy is not reachable within timeout
      */
-    protected function waitUntil($ip, $port, $timeout)
+    protected function waitUntil(string $ip, int $port, int $timeout): void
     {
         if (!$this->wait(
             $timeout,
@@ -77,7 +73,7 @@ function () use ($ip, $port) {
         }
     }
 
-    protected function wait($timeout, $callback)
+    protected function wait(int $timeout, callable $callback): bool
     {
         for ($i = 0; $i < $timeout; ++$i) {
             if ($callback()) {
@@ -93,11 +89,9 @@ protected function wait($timeout, $callback)
     /**
      * Run a shell command.
      *
-     * @param string $command
-     *
      * @throws \RuntimeException If command execution fails
      */
-    protected function runCommand($command, array $arguments)
+    protected function runCommand(string $command, array $arguments): void
     {
         $process = new Process(array_merge([$command], $arguments));
         $process->run();
@@ -107,68 +101,40 @@ protected function runCommand($command, array $arguments)
         }
     }
 
-    /**
-     * @param int $port
-     */
-    public function setPort($port)
+    public function setPort(int $port): void
     {
         $this->port = $port;
     }
 
-    /**
-     * @return int
-     */
-    public function getPort()
+    public function getPort(): int
     {
         return $this->port;
     }
 
-    /**
-     * Set Varnish binary (defaults to varnishd).
-     *
-     * @param string $binary
-     */
-    public function setBinary($binary)
+    public function setBinary(string $binary): void
     {
         $this->binary = $binary;
     }
 
-    /**
-     * Get Varnish binary.
-     *
-     * @return string
-     */
-    public function getBinary()
+    public function getBinary(): string
     {
         return $this->binary;
     }
 
-    /**
-     * Set IP address (defaults to 127.0.0.1).
-     *
-     * @param string $ip
-     */
-    public function setIp($ip)
+    public function setIp(string $ip): void
     {
         $this->ip = $ip;
     }
 
-    /**
-     * Get IP address.
-     *
-     * @return string
-     */
-    public function getIp()
+    public function getIp(): string
     {
         return $this->ip;
     }
 
     /**
-     * @param string $configFile
-     *
      * @throws \InvalidArgumentException
      */
-    public function setConfigFile($configFile)
+    public function setConfigFile(string $configFile): void
     {
         if (!file_exists($configFile)) {
             throw new \InvalidArgumentException('Cannot find config file: '.$configFile);
@@ -177,10 +143,7 @@ public function setConfigFile($configFile)
         $this->configFile = $configFile;
     }
 
-    /**
-     * @return string
-     */
-    public function getConfigFile()
+    public function getConfigFile(): string
     {
         return $this->configFile;
     }
diff --git a/src/Test/Proxy/NginxProxy.php b/src/Test/Proxy/NginxProxy.php
index 727094cbf..d0d104757 100644
--- a/src/Test/Proxy/NginxProxy.php
+++ b/src/Test/Proxy/NginxProxy.php
@@ -13,28 +13,23 @@
 
 class NginxProxy extends AbstractProxy
 {
-    protected $binary = 'nginx';
+    protected string $binary = 'nginx';
 
-    protected $configFile;
+    protected string $configFile;
 
-    protected $port = 8080;
+    protected int $port = 8080;
 
-    protected $pid = '/tmp/foshttpcache-nginx.pid';
+    protected string $pid = '/tmp/foshttpcache-nginx.pid';
 
-    protected $cacheDir;
+    protected string $cacheDir;
 
-    /**
-     * Constructor.
-     *
-     * @param string $configFile Path to NGINX configuration file
-     */
-    public function __construct($configFile)
+    public function __construct(string $configFile)
     {
         $this->setConfigFile($configFile);
         $this->setCacheDir(sys_get_temp_dir().DIRECTORY_SEPARATOR.'foshttpcache-nginx');
     }
 
-    public function start()
+    public function start(): void
     {
         $this->runCommand(
             $this->getBinary(),
@@ -47,31 +42,25 @@ public function start()
         $this->waitFor($this->getIp(), $this->getPort(), 2000);
     }
 
-    public function stop()
+    public function stop(): void
     {
         if (file_exists($this->pid)) {
             $this->runCommand('kill', [trim(file_get_contents($this->pid))]);
         }
     }
 
-    public function clear()
+    public function clear(): void
     {
         $this->runCommand('rm', ['-rf', $this->getCacheDir()]);
         $this->start();
     }
 
-    /**
-     * @param string $cacheDir
-     */
-    public function setCacheDir($cacheDir)
+    public function setCacheDir(string $cacheDir): void
     {
         $this->cacheDir = $cacheDir;
     }
 
-    /**
-     * @return string
-     */
-    public function getCacheDir()
+    public function getCacheDir(): string
     {
         return $this->cacheDir;
     }
diff --git a/src/Test/Proxy/ProxyInterface.php b/src/Test/Proxy/ProxyInterface.php
index 52e35d6a2..3122e7cc2 100644
--- a/src/Test/Proxy/ProxyInterface.php
+++ b/src/Test/Proxy/ProxyInterface.php
@@ -19,15 +19,15 @@ interface ProxyInterface
     /**
      * Start the proxy server.
      */
-    public function start();
+    public function start(): void;
 
     /**
      * Stop the proxy server.
      */
-    public function stop();
+    public function stop(): void;
 
     /**
      * Clear all cached content from the proxy server.
      */
-    public function clear();
+    public function clear(): void;
 }
diff --git a/src/Test/Proxy/SymfonyProxy.php b/src/Test/Proxy/SymfonyProxy.php
index 87aacd3f4..adee4db4c 100644
--- a/src/Test/Proxy/SymfonyProxy.php
+++ b/src/Test/Proxy/SymfonyProxy.php
@@ -19,12 +19,7 @@
  */
 class SymfonyProxy implements ProxyInterface
 {
-    /**
-     * Get Symfony cache directory.
-     *
-     * @return string
-     */
-    public function getCacheDir()
+    public function getCacheDir(): string
     {
         $path = defined('SYMFONY_CACHE_DIR') ? SYMFONY_CACHE_DIR : sys_get_temp_dir().'/foshttpcache-symfony';
         if (!$path || '/' === $path) {
@@ -34,26 +29,17 @@ public function getCacheDir()
         return $path;
     }
 
-    /**
-     * Start the proxy server.
-     */
-    public function start()
+    public function start(): void
     {
         $this->clear();
     }
 
-    /**
-     * Stop the proxy server.
-     */
-    public function stop()
+    public function stop(): void
     {
         // nothing to do
     }
 
-    /**
-     * Clear all cached content from the proxy server.
-     */
-    public function clear()
+    public function clear(): void
     {
         $path = realpath($this->getCacheDir());
 
@@ -63,7 +49,7 @@ public function clear()
         }
 
         $path = $this->getCacheDir();
-        if (0 === stripos(PHP_OS, 'WIN')) {
+        if (0 === stripos(PHP_OS_FAMILY, 'WIN')) {
             // @codeCoverageIgnoreStart
             system('DEL /S '.$path);
         } else {
diff --git a/src/Test/Proxy/VarnishProxy.php b/src/Test/Proxy/VarnishProxy.php
index e104c2437..ef248b0d0 100644
--- a/src/Test/Proxy/VarnishProxy.php
+++ b/src/Test/Proxy/VarnishProxy.php
@@ -13,34 +13,32 @@
 
 class VarnishProxy extends AbstractProxy
 {
-    protected $binary = 'varnishd';
+    protected string $binary = 'varnishd';
 
-    protected $port = 6181;
+    protected int $port = 6181;
 
-    protected $managementPort = 6182;
+    protected int $managementPort = 6182;
 
-    protected $pid = '/tmp/foshttpcache-varnish.pid';
+    protected string $pid = '/tmp/foshttpcache-varnish.pid';
 
-    protected $configFile;
+    protected string $configFile;
 
-    protected $configDir;
+    protected ?string $configDir = null;
 
-    protected $cacheDir;
+    protected string $cacheDir;
 
-    protected $allowInlineC = false;
+    protected bool $allowInlineC = false;
 
     /**
-     * Constructor.
-     *
      * @param string $configFile Path to VCL file
      */
-    public function __construct($configFile)
+    public function __construct(string $configFile)
     {
         $this->setConfigFile($configFile);
         $this->setCacheDir(sys_get_temp_dir().DIRECTORY_SEPARATOR.'foshttpcache-varnish');
     }
 
-    public function start()
+    public function start(): void
     {
         $vclPath = ((int) $this->getVarnishVersion()) >= 5 ? 'vcl_path' : 'vcl_dir';
 
@@ -63,7 +61,7 @@ public function start()
         $this->waitFor($this->ip, $this->getPort(), 5000);
     }
 
-    public function stop()
+    public function stop(): void
     {
         if (file_exists($this->pid)) {
             try {
@@ -76,26 +74,20 @@ public function stop()
         }
     }
 
-    public function clear()
+    public function clear(): void
     {
         $this->stop();
         $this->start();
     }
 
-    /**
-     * @param string $configDir
-     */
-    public function setConfigDir($configDir)
+    public function setConfigDir(string $configDir): void
     {
         $this->configDir = $configDir;
     }
 
-    /**
-     * @return string
-     */
-    public function getConfigDir()
+    public function getConfigDir(): string
     {
-        if (null === $this->configDir && null !== $this->configFile) {
+        if (null === $this->configDir) {
             return dirname(realpath($this->getConfigFile()));
         }
 
@@ -104,70 +96,38 @@ public function getConfigDir()
 
     /**
      * Set Varnish management port (defaults to 6182).
-     *
-     * @param int $managementPort
      */
-    public function setManagementPort($managementPort)
+    public function setManagementPort(int $managementPort): void
     {
         $this->managementPort = $managementPort;
     }
 
-    /**
-     * Get Varnish management port.
-     *
-     * @return int
-     */
-    public function getManagementPort()
+    public function getManagementPort(): int
     {
         return $this->managementPort;
     }
 
-    /**
-     * Set Varnish cache directory.
-     *
-     * @param string $cacheDir
-     */
-    public function setCacheDir($cacheDir)
+    public function setCacheDir(string $cacheDir): void
     {
         $this->cacheDir = $cacheDir;
     }
 
-    /**
-     * Get Varnish cache directory.
-     *
-     * @return string
-     */
-    public function getCacheDir()
+    public function getCacheDir(): string
     {
         return $this->cacheDir;
     }
 
-    /**
-     * Whether the inline C flag should be set.
-     *
-     * @return bool
-     */
-    public function getAllowInlineC()
+    public function getAllowInlineC(): bool
     {
         return $this->allowInlineC;
     }
 
-    /**
-     * Set whether the inline c flag should be on or off.
-     *
-     * @param bool $allowInlineC True for on, false for off
-     */
-    public function setAllowInlineC($allowInlineC)
+    public function setAllowInlineC(bool $allowInlineC): void
     {
         $this->allowInlineC = (bool) $allowInlineC;
     }
 
-    /**
-     * Defaults to 4.
-     *
-     * @return int
-     */
-    private function getVarnishVersion()
+    private function getVarnishVersion(): string
     {
         return getenv('VARNISH_VERSION') ?: '4.0';
     }
diff --git a/src/Test/SymfonyTest.php b/src/Test/SymfonyTest.php
index e7cd63bd0..eb65e3bac 100644
--- a/src/Test/SymfonyTest.php
+++ b/src/Test/SymfonyTest.php
@@ -35,15 +35,8 @@
  */
 trait SymfonyTest
 {
-    /**
-     * @var Symfony
-     */
-    protected $proxyClient;
-
-    /**
-     * @var SymfonyProxy
-     */
-    protected $proxy;
+    protected Symfony $proxyClient;
+    protected SymfonyProxy $proxy;
 
     /**
      * Clear Symfony HttpCache.
@@ -58,11 +51,9 @@ protected function setUp(): void
     /**
      * Get server port.
      *
-     * @return int
-     *
      * @throws \Exception
      */
-    protected function getCachingProxyPort()
+    protected function getCachingProxyPort(): int
     {
         // @codeCoverageIgnoreStart
         if (!defined('WEB_SERVER_PORT')) {
@@ -76,11 +67,9 @@ protected function getCachingProxyPort()
     /**
      * Get the hostname where your application can be reached.
      *
-     * @return string
-     *
      * @throws \Exception
      */
-    protected function getHostName()
+    protected function getHostName(): string
     {
         // @codeCoverageIgnoreStart
         if (!defined('WEB_SERVER_HOSTNAME')) {
@@ -93,12 +82,9 @@ protected function getHostName()
         return WEB_SERVER_HOSTNAME;
     }
 
-    /**
-     * @return SymfonyProxy
-     */
-    protected function getProxy()
+    protected function getProxy(): SymfonyProxy
     {
-        if (null === $this->proxy) {
+        if (!isset($this->proxy)) {
             $this->proxy = new SymfonyProxy();
         }
 
@@ -111,12 +97,10 @@ protected function getProxy()
      * We use a non-default method for PURGE because the built-in PHP webserver
      * does not allow arbitrary HTTP methods.
      * https://github.com/php/php-src/blob/PHP-5.4.1/sapi/cli/php_http_parser.c#L78-L102
-     *
-     * @return Symfony
      */
-    protected function getProxyClient()
+    protected function getProxyClient(): Symfony
     {
-        if (null === $this->proxyClient) {
+        if (!isset($this->proxyClient)) {
             $httpDispatcher = new HttpDispatcher(
                 ['http://127.0.0.1:'.$this->getCachingProxyPort()],
                 $this->getHostName().':'.$this->getCachingProxyPort()
diff --git a/src/Test/VarnishTest.php b/src/Test/VarnishTest.php
index 6dc5f7594..409378991 100644
--- a/src/Test/VarnishTest.php
+++ b/src/Test/VarnishTest.php
@@ -46,15 +46,9 @@
  */
 trait VarnishTest
 {
-    /**
-     * @var VarnishProxy
-     */
-    protected $proxy;
+    protected VarnishProxy $proxy;
 
-    /**
-     * @var Varnish
-     */
-    protected $proxyClient;
+    protected Varnish $proxyClient;
 
     /**
      * Start Varnish and discard any cached content.
@@ -79,7 +73,7 @@ protected function tearDown(): void
      *
      * @throws \Exception
      */
-    protected function getConfigFile()
+    protected function getConfigFile(): string
     {
         // @codeCoverageIgnoreStart
         if (!defined('VARNISH_FILE')) {
@@ -93,58 +87,48 @@ protected function getConfigFile()
     }
 
     /**
-     * Get Varnish binary.
-     *
-     * @return string
+     * Get path to Varnish binary.
      */
-    protected function getBinary()
+    protected function getBinary(): ?string
     {
         return defined('VARNISH_BINARY') ? VARNISH_BINARY : null;
     }
 
     /**
      * Get Varnish port.
-     *
-     * @return int
      */
-    protected function getCachingProxyPort()
+    protected function getCachingProxyPort(): int
     {
         return defined('VARNISH_PORT') ? VARNISH_PORT : 6181;
     }
 
     /**
      * Get Varnish management port.
-     *
-     * @return int
      */
-    protected function getVarnishMgmtPort()
+    protected function getVarnishMgmtPort(): ?int
     {
         return defined('VARNISH_MGMT_PORT') ? VARNISH_MGMT_PORT : null;
     }
 
     /**
      * Get Varnish cache directory.
-     *
-     * @return string
      */
-    protected function getCacheDir()
+    protected function getCacheDir(): ?string
     {
         return defined('VARNISH_CACHE_DIR') ? VARNISH_CACHE_DIR : null;
     }
 
     /**
      * Defaults to 4.
-     *
-     * @return int
      */
-    protected function getVarnishVersion()
+    protected function getVarnishVersion(): string
     {
         return getenv('VARNISH_VERSION') ?: '4.0';
     }
 
-    protected function getProxy()
+    protected function getProxy(): VarnishProxy
     {
-        if (null === $this->proxy) {
+        if (!isset($this->proxy)) {
             $this->proxy = new VarnishProxy($this->getConfigFile());
             if ($this->getBinary()) {
                 $this->proxy->setBinary($this->getBinary());
@@ -166,14 +150,9 @@ protected function getProxy()
         return $this->proxy;
     }
 
-    /**
-     * Get Varnish proxy client.
-     *
-     * @return Varnish
-     */
-    protected function getProxyClient()
+    protected function getProxyClient(): Varnish
     {
-        if (null === $this->proxyClient) {
+        if (!isset($this->proxyClient)) {
             $httpDispatcher = new HttpDispatcher(
                 ['http://127.0.0.1:'.$this->getCachingProxyPort()],
                 $this->getHostName().':'.$this->getCachingProxyPort()
@@ -197,11 +176,9 @@ protected function getProxyClient()
     /**
      * Get the hostname where your application can be reached.
      *
-     * @return string
-     *
      * @throws \Exception
      */
-    protected function getHostName()
+    protected function getHostName(): string
     {
         // @codeCoverageIgnoreStart
         if (!defined('WEB_SERVER_HOSTNAME')) {
diff --git a/src/UserContext/AnonymousRequestMatcher.php b/src/UserContext/AnonymousRequestMatcher.php
index 6eaffdff2..cc2e05995 100644
--- a/src/UserContext/AnonymousRequestMatcher.php
+++ b/src/UserContext/AnonymousRequestMatcher.php
@@ -20,10 +20,7 @@
  */
 class AnonymousRequestMatcher implements RequestMatcherInterface
 {
-    /**
-     * @var array
-     */
-    private $options;
+    private array $options;
 
     /**
      * @param array $options Configuration for the matcher. All options are required because this matcher is usually
@@ -56,7 +53,7 @@ public function matches(Request $request): bool
 
         if ($this->options['session_name_prefix']) {
             foreach ($request->cookies as $name => $value) {
-                if (0 === strpos($name, $this->options['session_name_prefix'])) {
+                if (str_starts_with($name, $this->options['session_name_prefix'])) {
                     return false;
                 }
             }
diff --git a/src/UserContext/DefaultHashGenerator.php b/src/UserContext/DefaultHashGenerator.php
index d9ba86133..edf013d35 100644
--- a/src/UserContext/DefaultHashGenerator.php
+++ b/src/UserContext/DefaultHashGenerator.php
@@ -21,7 +21,7 @@ class DefaultHashGenerator implements HashGenerator
     /**
      * @var ContextProvider[]
      */
-    private $providers = [];
+    private array $providers = [];
 
     /**
      * Constructor.
@@ -43,10 +43,8 @@ public function __construct(array $providers)
 
     /**
      * Collect UserContext parameters and generate a hash from that.
-     *
-     * @return string The hash generated
      */
-    public function generateHash()
+    public function generateHash(): string
     {
         $userContext = new UserContext();
 
@@ -67,7 +65,7 @@ public function generateHash()
      *
      * @param ContextProvider $provider A context provider to be called to get context information about the current request
      */
-    private function registerProvider(ContextProvider $provider)
+    private function registerProvider(ContextProvider $provider): void
     {
         $this->providers[] = $provider;
     }
diff --git a/src/UserContext/HashGenerator.php b/src/UserContext/HashGenerator.php
index 42c987074..de17235fc 100644
--- a/src/UserContext/HashGenerator.php
+++ b/src/UserContext/HashGenerator.php
@@ -12,12 +12,9 @@
 namespace FOS\HttpCache\UserContext;
 
 /**
- * Generate a hash.
+ * Generate a hash for distinguishing user contexts.
  */
 interface HashGenerator
 {
-    /**
-     * @return string The hash generated
-     */
-    public function generateHash();
+    public function generateHash(): string;
 }
diff --git a/src/UserContext/UserContext.php b/src/UserContext/UserContext.php
index 0de3309aa..4b942e4c1 100644
--- a/src/UserContext/UserContext.php
+++ b/src/UserContext/UserContext.php
@@ -20,15 +20,17 @@
  */
 class UserContext implements \IteratorAggregate
 {
-    private $parameters = [];
+    /**
+     * @var array<string, mixed>
+     */
+    private array $parameters = [];
 
     /**
      * Set a parameter for this context.
      *
-     * @param string $key   Parameter identifier
-     * @param mixed  $value Parameter value (it should be serializable)
+     * @param mixed $value Parameter value (it should be serializable)
      */
-    public function addParameter($key, $value)
+    public function addParameter(string $key, $value): void
     {
         $this->parameters[$key] = $value;
     }
@@ -36,19 +38,15 @@ public function addParameter($key, $value)
     /**
      * Set all the parameters of this context.
      */
-    public function setParameters(array $parameters)
+    public function setParameters(array $parameters): void
     {
         $this->parameters = $parameters;
     }
 
     /**
      * Determine whether a parameter exists.
-     *
-     * @param string $key
-     *
-     * @return bool
      */
-    public function hasParameter($key)
+    public function hasParameter(string $key): bool
     {
         return array_key_exists($key, $this->parameters);
     }
@@ -56,9 +54,9 @@ public function hasParameter($key)
     /**
      * Return all parameters of this context.
      *
-     * @return array
+     * @return array<string, mixed>
      */
-    public function getParameters()
+    public function getParameters(): array
     {
         return $this->parameters;
     }
diff --git a/tests/Functional/Varnish/UserContextFailureTest.php b/tests/Functional/Varnish/UserContextFailureTest.php
index 977d3e262..0108be76f 100644
--- a/tests/Functional/Varnish/UserContextFailureTest.php
+++ b/tests/Functional/Varnish/UserContextFailureTest.php
@@ -93,13 +93,11 @@ public function testHashRequestFailure(): void
         $this->assertEquals(503, $response->getStatusCode());
     }
 
-    protected function getConfigFile(): ?string
+    protected function getConfigFile(): string
     {
-        switch ((int) $this->getVarnishVersion()) {
-            case 3:
-                return sprintf(dirname(__DIR__).'/Fixtures/varnish-3/user_context_%s.vcl', $this->mode);
-            default:
-                return sprintf(dirname(__DIR__).'/Fixtures/varnish/user_context_%s.vcl', $this->mode);
-        }
+        return match ((int) $this->getVarnishVersion()) {
+            3 => sprintf(dirname(__DIR__).'/Fixtures/varnish-3/user_context_%s.vcl', $this->mode),
+            default => sprintf(dirname(__DIR__).'/Fixtures/varnish/user_context_%s.vcl', $this->mode),
+        };
     }
 }
diff --git a/tests/Functional/Varnish/UserContextNocacheTest.php b/tests/Functional/Varnish/UserContextNocacheTest.php
index e93313856..4f7c613d5 100644
--- a/tests/Functional/Varnish/UserContextNocacheTest.php
+++ b/tests/Functional/Varnish/UserContextNocacheTest.php
@@ -17,14 +17,12 @@
  */
 class UserContextNocacheTest extends UserContextTestCase
 {
-    protected function getConfigFile(): ?string
+    protected function getConfigFile(): string
     {
-        switch ((int) $this->getVarnishVersion()) {
-            case 3:
-                return dirname(__DIR__).'/Fixtures/varnish-3/user_context_nocache.vcl';
-            default:
-                return dirname(__DIR__).'/Fixtures/varnish/user_context_nocache.vcl';
-        }
+        return match ((int) $this->getVarnishVersion()) {
+            3 => dirname(__DIR__).'/Fixtures/varnish-3/user_context_nocache.vcl',
+            default => dirname(__DIR__).'/Fixtures/varnish/user_context_nocache.vcl',
+        };
     }
 
     protected function assertContextCache(string $hashCache): void
diff --git a/tests/Unit/ProxyClient/HttpDispatcherTest.php b/tests/Unit/ProxyClient/HttpDispatcherTest.php
index 198082bfe..ce26f96c5 100644
--- a/tests/Unit/ProxyClient/HttpDispatcherTest.php
+++ b/tests/Unit/ProxyClient/HttpDispatcherTest.php
@@ -49,17 +49,6 @@ protected function setUp(): void
         $this->uriFactory = UriFactoryDiscovery::find();
     }
 
-    public function testInstantiateWithNonUri(): void
-    {
-        $this->expectException(\InvalidArgumentException::class);
-        $this->expectExceptionMessage('URI parameter must be a string, object given');
-
-        new HttpDispatcher(
-            ['127.0.0.1:123'],
-            $this
-        );
-    }
-
     /**
      * @dataProvider exceptionProvider
      *
diff --git a/tests/Unit/ResponseTaggerTest.php b/tests/Unit/ResponseTaggerTest.php
index 59c83130e..d87537f24 100644
--- a/tests/Unit/ResponseTaggerTest.php
+++ b/tests/Unit/ResponseTaggerTest.php
@@ -23,13 +23,13 @@ class ResponseTaggerTest extends TestCase
 {
     use MockeryPHPUnitIntegration;
 
-    public function testDefaultFormatter()
+    public function testDefaultFormatter(): void
     {
         $tagger = new ResponseTagger();
         $this->assertEquals('X-Cache-Tags', $tagger->getTagsHeaderName());
     }
 
-    public function testGetTagsHeaderValue()
+    public function testGetTagsHeaderValue(): void
     {
         $headerFormatter = \Mockery::mock(TagHeaderFormatter::class)
             ->shouldReceive('getTagsHeaderValue')
@@ -46,7 +46,7 @@ public function testGetTagsHeaderValue()
         $this->assertTrue($tagger->hasTags()); // getting the header does not clear the tags
     }
 
-    public function testTagResponseReplace()
+    public function testTagResponseReplace(): void
     {
         $headerFormatter = \Mockery::mock(TagHeaderFormatter::class)
             ->shouldReceive('getTagsHeaderValue')
@@ -63,6 +63,7 @@ public function testTagResponseReplace()
         $response = \Mockery::mock(ResponseInterface::class)
             ->shouldReceive('withHeader')
             ->with('FOS-Tags', 'tag-1,tag-2')
+            ->andReturn($this->createMock(ResponseInterface::class))
             ->getMock();
 
         $tagger->addTags(['tag-1', 'tag-2']);
@@ -70,7 +71,7 @@ public function testTagResponseReplace()
         $this->assertFalse($tagger->hasTags());
     }
 
-    public function testTagResponseAdd()
+    public function testTagResponseAdd(): void
     {
         $headerFormatter = \Mockery::mock(TagHeaderFormatter::class)
             ->shouldReceive('getTagsHeaderValue')
@@ -87,6 +88,7 @@ public function testTagResponseAdd()
         $response = \Mockery::mock(ResponseInterface::class)
             ->shouldReceive('withAddedHeader')
             ->with('FOS-Tags', 'tag-1,tag-2')
+            ->andReturn($this->createMock(ResponseInterface::class))
             ->getMock();
 
         $tagger->addTags(['tag-1', 'tag-2']);
@@ -94,7 +96,7 @@ public function testTagResponseAdd()
         $this->assertFalse($tagger->hasTags());
     }
 
-    public function testTagResponseNoTags()
+    public function testTagResponseNoTags(): void
     {
         /** @var TagHeaderFormatter $headerFormatter */
         $headerFormatter = \Mockery::mock(TagHeaderFormatter::class)
@@ -111,7 +113,7 @@ public function testTagResponseNoTags()
         $tagger->tagResponse($response, true);
     }
 
-    public function testStrictEmptyTag()
+    public function testStrictEmptyTag(): void
     {
         $headerFormatter = new CommaSeparatedTagHeaderFormatter('FOS-Tags');
 
@@ -121,7 +123,7 @@ public function testStrictEmptyTag()
         $tagHandler->addTags(['post-1', false]);
     }
 
-    public function testNonStrictEmptyTag()
+    public function testNonStrictEmptyTag(): void
     {
         $headerFormatter = \Mockery::mock(TagHeaderFormatter::class)
             ->shouldReceive('getTagsHeaderValue')
@@ -136,7 +138,7 @@ public function testNonStrictEmptyTag()
         $this->assertEquals('post-1', $tagHandler->getTagsHeaderValue());
     }
 
-    public function testUniqueTags()
+    public function testUniqueTags(): void
     {
         $headerFormatter = new CommaSeparatedTagHeaderFormatter('FOS-Tags');
 
@@ -148,7 +150,7 @@ public function testUniqueTags()
         $this->assertEquals('post-1,post-2,post-3', $tagHandler->getTagsHeaderValue());
     }
 
-    public function testClear()
+    public function testClear(): void
     {
         $tagger = new ResponseTagger();
         $this->assertFalse($tagger->hasTags());
diff --git a/tests/Unit/Test/Proxy/AbstractProxyTest.php b/tests/Unit/Test/Proxy/AbstractProxyTest.php
index 083ac61d4..1366f91ef 100644
--- a/tests/Unit/Test/Proxy/AbstractProxyTest.php
+++ b/tests/Unit/Test/Proxy/AbstractProxyTest.php
@@ -16,7 +16,7 @@
 
 class AbstractProxyTest extends TestCase
 {
-    public function testWaitTimeout()
+    public function testWaitTimeout(): void
     {
         $proxy = new ProxyPartial();
         $this->expectException(\RuntimeException::class);
@@ -24,7 +24,7 @@ public function testWaitTimeout()
         $proxy->start();
     }
 
-    public function testRunFailure()
+    public function testRunFailure(): void
     {
         $proxy = new ProxyPartial();
         $this->expectException(\RuntimeException::class);
@@ -35,20 +35,20 @@ public function testRunFailure()
 
 class ProxyPartial extends AbstractProxy
 {
-    public function start()
+    public function start(): void
     {
         $this->waitUntil('localhost', 6666, 0);
     }
 
-    public function stop()
+    public function stop(): void
     {
     }
 
-    public function clear()
+    public function clear(): void
     {
     }
 
-    public function run()
+    public function run(): void
     {
         $this->runCommand('/path/to/not/exists', []);
     }
diff --git a/tests/Unit/Test/Proxy/VarnishProxyTest.php b/tests/Unit/Test/Proxy/VarnishProxyTest.php
index 2a1e85686..21467a1ac 100644
--- a/tests/Unit/Test/Proxy/VarnishProxyTest.php
+++ b/tests/Unit/Test/Proxy/VarnishProxyTest.php
@@ -16,7 +16,7 @@
 
 class VarnishProxyTest extends TestCase
 {
-    public function testInvalidConfigFileThrowsException()
+    public function testInvalidConfigFileThrowsException(): void
     {
         $this->expectException(\InvalidArgumentException::class);
         $this->expectExceptionMessage('Cannot find config file: nope.vcl');
@@ -24,7 +24,7 @@ public function testInvalidConfigFileThrowsException()
         new VarnishProxy('nope.vcl');
     }
 
-    public function allowInlineFlagProvider()
+    public function allowInlineFlagProvider(): array
     {
         return [[true], [false]];
     }
@@ -32,7 +32,7 @@ public function allowInlineFlagProvider()
     /**
      * @dataProvider allowInlineFlagProvider
      */
-    public function testStart($inlineC)
+    public function testStart(bool $inlineC): void
     {
         $proxy = new VarnishProxyMock('config.vcl');
         $proxy->setBinary('/usr/sbin/varnishd');
@@ -75,24 +75,24 @@ public function testWaitThrowsException()
 
 class VarnishProxyMock extends VarnishProxy
 {
-    public $command;
+    public string $command;
 
-    public $arguments;
+    public array $arguments;
 
-    public $wait = true;
+    public bool $wait = true;
 
-    public function setConfigFile($configFile)
+    public function setConfigFile(string $configFile): void
     {
         $this->configFile = $configFile;
     }
 
-    protected function runCommand($command, array $arguments)
+    protected function runCommand(string $command, array $arguments): void
     {
         $this->command = $command;
         $this->arguments = $arguments;
     }
 
-    protected function wait($timeout, $callback)
+    protected function wait($timeout, $callback): bool
     {
         return $this->wait;
     }