diff --git a/composer.json b/composer.json
index 2eb548d..fb19fc3 100644
--- a/composer.json
+++ b/composer.json
@@ -20,8 +20,10 @@
     "require-dev": {
         "doctrine/instantiator": "^1.1",
         "guzzlehttp/psr7": "^1.4",
+        "nyholm/psr7": "^1.2",
         "phpspec/phpspec": "^5.1 || ^6.0",
         "phpspec/prophecy": "^1.8",
+        "phpunit/phpunit": "^7.5",
         "sebastian/comparator": "^3.0"
     },
     "suggest": {
@@ -42,8 +44,17 @@
         }
     },
     "scripts": {
-        "test": "vendor/bin/phpspec run",
-        "test-ci": "vendor/bin/phpspec run -c phpspec.ci.yml"
+        "test": [
+            "vendor/bin/phpspec run",
+            "vendor/bin/phpunit"
+        ],
+        "test-ci": [
+            "vendor/bin/phpspec run -c phpspec.ci.yml",
+            "vendor/bin/phpunit"
+        ]
+    },
+    "config": {
+        "sort-packages": true
     },
     "extra": {
         "branch-alias": {
diff --git a/tests/Plugin/AddPathPluginTest.php b/tests/Plugin/AddPathPluginTest.php
index 3980fa4..55081a8 100644
--- a/tests/Plugin/AddPathPluginTest.php
+++ b/tests/Plugin/AddPathPluginTest.php
@@ -4,8 +4,7 @@
 
 use Http\Client\Common\Plugin;
 use Http\Client\Common\Plugin\AddPathPlugin;
-use Http\Client\Common\PluginClient;
-use Http\Client\HttpClient;
+use Http\Client\Promise\HttpFulfilledPromise;
 use Nyholm\Psr7\Request;
 use Nyholm\Psr7\Response;
 use Nyholm\Psr7\Uri;
@@ -24,7 +23,7 @@ class AddPathPluginTest extends TestCase
      */
     private $first;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->first = function () {};
         $this->plugin = new AddPathPlugin(new Uri('/api'));
@@ -34,16 +33,18 @@ public function testRewriteSameUrl()
     {
         $verify = function (RequestInterface $request) {
             $this->assertEquals('https://example.com/api/foo', $request->getUri()->__toString());
+
+            return new HttpFulfilledPromise(new Response());
         };
 
-        $request = new Request('GET', 'https://example.com/foo', ['Content-Type'=>'text/html']);
+        $request = new Request('GET', 'https://example.com/foo', ['Content-Type' => 'text/html']);
         $this->plugin->handleRequest($request, $verify, $this->first);
 
         // Make a second call with the same $request object
         $this->plugin->handleRequest($request, $verify, $this->first);
 
         // Make a new call with a new object but same URL
-        $request = new Request('GET', 'https://example.com/foo', ['Content-Type'=>'text/plain']);
+        $request = new Request('GET', 'https://example.com/foo', ['Content-Type' => 'text/plain']);
         $this->plugin->handleRequest($request, $verify, $this->first);
     }
 
@@ -56,7 +57,11 @@ public function testRewriteCallingThePluginTwice()
             // Run the plugin again with the modified request
             $this->plugin->handleRequest($request, function (RequestInterface $request) {
                 $this->assertEquals('https://example.com/api/foo', $request->getUri()->__toString());
+
+                return new HttpFulfilledPromise(new Response());
             }, $this->first);
+
+            return new HttpFulfilledPromise(new Response());
         }, $this->first);
     }
 
@@ -65,11 +70,15 @@ public function testRewriteWithDifferentUrl()
         $request = new Request('GET', 'https://example.com/foo');
         $this->plugin->handleRequest($request, function (RequestInterface $request) {
             $this->assertEquals('https://example.com/api/foo', $request->getUri()->__toString());
+
+            return new HttpFulfilledPromise(new Response());
         }, $this->first);
 
         $request = new Request('GET', 'https://example.com/bar');
         $this->plugin->handleRequest($request, function (RequestInterface $request) {
             $this->assertEquals('https://example.com/api/bar', $request->getUri()->__toString());
+
+            return new HttpFulfilledPromise(new Response());
         }, $this->first);
     }
 
@@ -77,6 +86,8 @@ public function testRewriteWhenPathIsIncluded()
     {
         $verify = function (RequestInterface $request) {
             $this->assertEquals('https://example.com/api/foo', $request->getUri()->__toString());
+
+            return new HttpFulfilledPromise(new Response());
         };
 
         $request = new Request('GET', 'https://example.com/api/foo');