diff --git a/phpunit.xml b/phpunit.xml
index 69222a4..cf35759 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -1,13 +1,22 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" backupGlobals="false" backupStaticAttributes="false" bootstrap="vendor/autoload.php" colors="true" convertErrorsToExceptions="true" convertNoticesToExceptions="true" convertWarningsToExceptions="true" processIsolation="false" stopOnFailure="false" xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd">
-  <coverage processUncoveredFiles="true">
-    <include>
-      <directory suffix=".php">./src</directory>
-    </include>
-  </coverage>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+  backupGlobals="false"
+  bootstrap="vendor/autoload.php"
+  colors="true"
+  processIsolation="false"
+  stopOnFailure="false"
+  xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/10.5/phpunit.xsd"
+  cacheDirectory=".phpunit.cache"
+  backupStaticProperties="false"
+>
   <testsuites>
     <testsuite name="Package Test Suite">
       <directory suffix=".php">./tests/</directory>
     </testsuite>
   </testsuites>
+  <source>
+    <include>
+      <directory suffix=".php">./src</directory>
+    </include>
+  </source>
 </phpunit>
diff --git a/tests/src/Provider/MollieTest.php b/tests/src/Provider/MollieTest.php
index afb9915..cccc1c4 100644
--- a/tests/src/Provider/MollieTest.php
+++ b/tests/src/Provider/MollieTest.php
@@ -3,6 +3,7 @@
 namespace Mollie\OAuth2\Client\Test\Provider;
 
 use GuzzleHttp\ClientInterface;
+use GuzzleHttp\Psr7\Request;
 use GuzzleHttp\Psr7\Utils;
 use League\OAuth2\Client\Provider\Exception\IdentityProviderException;
 use League\OAuth2\Client\Token\AccessToken;
@@ -62,7 +63,7 @@ public function testAuthorizationUrl()
     {
         $authUrl = $this->provider->getAuthorizationUrl();
 
-        list($url, $queryString) = explode('?', $authUrl);
+        [$url, $queryString] = explode('?', $authUrl);
         parse_str($queryString, $query);
 
         $this->assertEquals('https://my.mollie.com/oauth2/authorize', $url);
@@ -94,7 +95,24 @@ public function testGetAccessToken()
         $response->shouldReceive('getStatusCode')->andReturn(200);
 
         $client = m::mock(ClientInterface::class);
-        $client->shouldReceive('send')->times(1)->andReturn($response);
+        $client->shouldReceive('send')
+            ->times(1)
+            ->withArgs(function (Request $request) {
+                $this->assertEquals('POST', $request->getMethod());
+                $this->assertEquals('https://api.mollie.com/oauth2/tokens', $request->getUri()->__toString());
+                $body = $request->getBody()->__toString();
+                parse_str($body, $params);
+
+                $this->assertEquals(self::MOCK_CLIENT_ID, $params['client_id']);
+                $this->assertEquals('mock_secret', $params['client_secret']);
+                $this->assertEquals(self::REDIRECT_URI, $params['redirect_uri']);
+                $this->assertEquals('authorization_code', $params['grant_type'] ?? null);
+                $this->assertEquals('mock_authorization_code', $params['code']);
+                $this->assertFalse(isset($params['scope']));
+
+                return true;
+            })
+            ->andReturn($response);
 
         $this->provider->setHttpClient($client);
 
@@ -293,7 +311,7 @@ public function testWhenDefiningADifferentMollieWebUrlThenUseThisForAuthorize()
     {
         $this->provider->setMollieWebUrl('https://www.mollie.nl');
 
-        list($url) = explode('?', $this->provider->getAuthorizationUrl());
+        [$url] = explode('?', $this->provider->getAuthorizationUrl());
         $this->assertEquals('https://www.mollie.nl/oauth2/authorize', $url);
     }
 }