diff --git a/.gitignore b/.gitignore
index 2e27c436..70efea11 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
+/.phpunit.result.cache
 /.php_cs.cache
 /behat.yml
 /build/
diff --git a/.php_cs.dist b/.php_cs.dist
index 8c7bcc22..b7475fd4 100644
--- a/.php_cs.dist
+++ b/.php_cs.dist
@@ -7,9 +7,11 @@ $finder = PhpCsFixer\Finder::create()
 ;
 
 return PhpCsFixer\Config::create()
+    ->setRiskyAllowed(true)
     ->setRules([
         '@Symfony' => true,
         'array_syntax' => ['syntax' => 'short'],
+        'declare_strict_types' => true,
         'visibility_required' => [
             'elements' => [
                 'const',
diff --git a/src/ClientFactory/AutoDiscoveryFactory.php b/src/ClientFactory/AutoDiscoveryFactory.php
index 78b64f78..1c2bf5b9 100644
--- a/src/ClientFactory/AutoDiscoveryFactory.php
+++ b/src/ClientFactory/AutoDiscoveryFactory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\ClientFactory;
 
 use Http\Discovery\HttpClientDiscovery;
diff --git a/src/ClientFactory/BuzzFactory.php b/src/ClientFactory/BuzzFactory.php
index 84f1e9d7..7ef64ca2 100644
--- a/src/ClientFactory/BuzzFactory.php
+++ b/src/ClientFactory/BuzzFactory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\ClientFactory;
 
 use Buzz\Client\FileGetContents;
diff --git a/src/ClientFactory/ClientFactory.php b/src/ClientFactory/ClientFactory.php
index 78a67a8a..6d0c600b 100644
--- a/src/ClientFactory/ClientFactory.php
+++ b/src/ClientFactory/ClientFactory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\ClientFactory;
 
 use Http\Client\HttpClient;
diff --git a/src/ClientFactory/CurlFactory.php b/src/ClientFactory/CurlFactory.php
index 6d65cdb8..3ef6b385 100644
--- a/src/ClientFactory/CurlFactory.php
+++ b/src/ClientFactory/CurlFactory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\ClientFactory;
 
 use Http\Client\Curl\Client;
diff --git a/src/ClientFactory/DummyClient.php b/src/ClientFactory/DummyClient.php
index 2fd6f1c4..09665e5e 100644
--- a/src/ClientFactory/DummyClient.php
+++ b/src/ClientFactory/DummyClient.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\ClientFactory;
 
 @trigger_error('The '.__NAMESPACE__.'\DummyClient interface is deprecated since version 1.7 and will be removed in 2.0.', E_USER_DEPRECATED);
diff --git a/src/ClientFactory/Guzzle5Factory.php b/src/ClientFactory/Guzzle5Factory.php
index 7f5824ae..82ecd13f 100644
--- a/src/ClientFactory/Guzzle5Factory.php
+++ b/src/ClientFactory/Guzzle5Factory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\ClientFactory;
 
 use GuzzleHttp\Client;
diff --git a/src/ClientFactory/Guzzle6Factory.php b/src/ClientFactory/Guzzle6Factory.php
index 802f9e52..92d9da46 100644
--- a/src/ClientFactory/Guzzle6Factory.php
+++ b/src/ClientFactory/Guzzle6Factory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\ClientFactory;
 
 use Http\Adapter\Guzzle6\Client;
diff --git a/src/ClientFactory/MockFactory.php b/src/ClientFactory/MockFactory.php
index c56d38c9..fa743109 100644
--- a/src/ClientFactory/MockFactory.php
+++ b/src/ClientFactory/MockFactory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\ClientFactory;
 
 use Http\Client\HttpClient;
diff --git a/src/ClientFactory/PluginClientFactory.php b/src/ClientFactory/PluginClientFactory.php
index 10092758..8821a174 100644
--- a/src/ClientFactory/PluginClientFactory.php
+++ b/src/ClientFactory/PluginClientFactory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\ClientFactory;
 
 @trigger_error('The '.__NAMESPACE__.'\PluginClientFactory class is deprecated since version 1.8 and will be removed in 2.0. Use Http\Client\Common\PluginClientFactory instead.', E_USER_DEPRECATED);
diff --git a/src/ClientFactory/ReactFactory.php b/src/ClientFactory/ReactFactory.php
index 1e8d6212..d1f90280 100644
--- a/src/ClientFactory/ReactFactory.php
+++ b/src/ClientFactory/ReactFactory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\ClientFactory;
 
 use Http\Adapter\React\Client;
diff --git a/src/ClientFactory/SocketFactory.php b/src/ClientFactory/SocketFactory.php
index 58c93fa6..c1e1016a 100644
--- a/src/ClientFactory/SocketFactory.php
+++ b/src/ClientFactory/SocketFactory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\ClientFactory;
 
 use Http\Client\Socket\Client;
diff --git a/src/ClientFactory/SymfonyFactory.php b/src/ClientFactory/SymfonyFactory.php
index 14a26225..21f1b529 100644
--- a/src/ClientFactory/SymfonyFactory.php
+++ b/src/ClientFactory/SymfonyFactory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\ClientFactory;
 
 use Psr\Http\Message\ResponseFactoryInterface;
diff --git a/src/Collector/Collector.php b/src/Collector/Collector.php
index 5001448d..20645639 100644
--- a/src/Collector/Collector.php
+++ b/src/Collector/Collector.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Collector;
 
 use Symfony\Component\HttpFoundation\Request;
diff --git a/src/Collector/Formatter.php b/src/Collector/Formatter.php
index e2eb9c12..80df7121 100644
--- a/src/Collector/Formatter.php
+++ b/src/Collector/Formatter.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Collector;
 
 use Exception;
diff --git a/src/Collector/PluginClientFactory.php b/src/Collector/PluginClientFactory.php
index 91c22216..6d8d0342 100644
--- a/src/Collector/PluginClientFactory.php
+++ b/src/Collector/PluginClientFactory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Collector;
 
 use Http\Client\Common\Plugin;
diff --git a/src/Collector/PluginClientFactoryListener.php b/src/Collector/PluginClientFactoryListener.php
index b86a402f..b51e82fc 100644
--- a/src/Collector/PluginClientFactoryListener.php
+++ b/src/Collector/PluginClientFactoryListener.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Collector;
 
 use Http\Client\Common\PluginClientFactory as DefaultPluginClientFactory;
diff --git a/src/Collector/Profile.php b/src/Collector/Profile.php
index 5543e216..1240effa 100644
--- a/src/Collector/Profile.php
+++ b/src/Collector/Profile.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Collector;
 
 /**
diff --git a/src/Collector/ProfileClient.php b/src/Collector/ProfileClient.php
index 318120ea..0110696e 100644
--- a/src/Collector/ProfileClient.php
+++ b/src/Collector/ProfileClient.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Collector;
 
 use Http\Client\Common\FlexibleHttpClient;
diff --git a/src/Collector/ProfileClientFactory.php b/src/Collector/ProfileClientFactory.php
index e2adffa4..7b5903b2 100644
--- a/src/Collector/ProfileClientFactory.php
+++ b/src/Collector/ProfileClientFactory.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Collector;
 
 use Http\Client\Common\FlexibleHttpClient;
diff --git a/src/Collector/ProfilePlugin.php b/src/Collector/ProfilePlugin.php
index b83da5f1..5808bfcf 100644
--- a/src/Collector/ProfilePlugin.php
+++ b/src/Collector/ProfilePlugin.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Collector;
 
 use Exception;
diff --git a/src/Collector/Stack.php b/src/Collector/Stack.php
index 755e9487..da905f3a 100644
--- a/src/Collector/Stack.php
+++ b/src/Collector/Stack.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Collector;
 
 /**
diff --git a/src/Collector/StackPlugin.php b/src/Collector/StackPlugin.php
index 0bb527d5..b8371fc5 100644
--- a/src/Collector/StackPlugin.php
+++ b/src/Collector/StackPlugin.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Collector;
 
 use Exception;
diff --git a/src/Collector/Twig/HttpMessageMarkupExtension.php b/src/Collector/Twig/HttpMessageMarkupExtension.php
index 88268793..a35922be 100644
--- a/src/Collector/Twig/HttpMessageMarkupExtension.php
+++ b/src/Collector/Twig/HttpMessageMarkupExtension.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Collector\Twig;
 
 use Twig\Extension\AbstractExtension;
diff --git a/src/DependencyInjection/Configuration.php b/src/DependencyInjection/Configuration.php
index e200ad81..ba128432 100644
--- a/src/DependencyInjection/Configuration.php
+++ b/src/DependencyInjection/Configuration.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\DependencyInjection;
 
 use Http\Client\Common\Plugin\Cache\Generator\CacheKeyGenerator;
diff --git a/src/DependencyInjection/HttplugExtension.php b/src/DependencyInjection/HttplugExtension.php
index 965e3390..957a5e27 100644
--- a/src/DependencyInjection/HttplugExtension.php
+++ b/src/DependencyInjection/HttplugExtension.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\DependencyInjection;
 
 use Http\Client\Common\BatchClient;
diff --git a/src/Discovery/ConfiguredClientsStrategy.php b/src/Discovery/ConfiguredClientsStrategy.php
index 212e1930..add66ac6 100644
--- a/src/Discovery/ConfiguredClientsStrategy.php
+++ b/src/Discovery/ConfiguredClientsStrategy.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Discovery;
 
 use Http\Client\HttpClient;
diff --git a/src/HttplugBundle.php b/src/HttplugBundle.php
index 082d32f4..d6aa836d 100644
--- a/src/HttplugBundle.php
+++ b/src/HttplugBundle.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle;
 
 use Symfony\Component\HttpKernel\Bundle\Bundle;
diff --git a/tests/Functional/DiscoveredClientsTest.php b/tests/Functional/DiscoveredClientsTest.php
index 7496c649..4525ef01 100644
--- a/tests/Functional/DiscoveredClientsTest.php
+++ b/tests/Functional/DiscoveredClientsTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Tests\Functional;
 
 use Http\Client\HttpAsyncClient;
@@ -11,9 +13,9 @@
 use Http\HttplugBundle\Discovery\ConfiguredClientsStrategy;
 use Nyholm\NSA;
 use Symfony\Bundle\FrameworkBundle\Test\WebTestCase;
+use Symfony\Component\EventDispatcher\Event as LegacyEvent;
 use Symfony\Component\HttpKernel\Kernel;
 use Symfony\Contracts\EventDispatcher\Event;
-use Symfony\Component\EventDispatcher\Event as LegacyEvent;
 
 class DiscoveredClientsTest extends WebTestCase
 {
diff --git a/tests/Functional/DiscoveryTest.php b/tests/Functional/DiscoveryTest.php
index 25168205..511aecec 100644
--- a/tests/Functional/DiscoveryTest.php
+++ b/tests/Functional/DiscoveryTest.php
@@ -1,7 +1,10 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Tests\Unit\DependencyInjection\Compiler;
 
+use Http\Adapter\Guzzle6\Client;
 use Http\Client\HttpAsyncClient;
 use Http\Client\HttpClient;
 use Http\Discovery\HttpClientDiscovery;
@@ -13,7 +16,6 @@
 use Matthias\SymfonyDependencyInjectionTest\PhpUnit\ContainerBuilderHasAliasConstraint;
 use PHPUnit\Framework\Constraint\LogicalNot;
 use Symfony\Component\DependencyInjection\Definition;
-use Http\Adapter\Guzzle6\Client;
 
 /**
  * @author Márk Sági-Kazár <mark.sagikazar@gmail.com>
diff --git a/tests/Functional/ProfilerTest.php b/tests/Functional/ProfilerTest.php
index d07f0044..92cead83 100644
--- a/tests/Functional/ProfilerTest.php
+++ b/tests/Functional/ProfilerTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Tests\Functional;
 
 use Symfony\Bundle\FrameworkBundle\Test\WebTestCase;
diff --git a/tests/Functional/ProfilingTest.php b/tests/Functional/ProfilingTest.php
index 1620c9a1..cdd0e2eb 100644
--- a/tests/Functional/ProfilingTest.php
+++ b/tests/Functional/ProfilingTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Tests\Functional;
 
 use GuzzleHttp\Psr7\Request;
diff --git a/tests/Functional/ServiceInstantiationTest.php b/tests/Functional/ServiceInstantiationTest.php
index ada23b32..aaceefa2 100644
--- a/tests/Functional/ServiceInstantiationTest.php
+++ b/tests/Functional/ServiceInstantiationTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Tests\Functional;
 
 use GuzzleHttp\Psr7\Request as GuzzleRequest;
diff --git a/tests/Unit/ClientFactory/BuzzFactoryTest.php b/tests/Unit/ClientFactory/BuzzFactoryTest.php
index c290ed36..f1f4020c 100644
--- a/tests/Unit/ClientFactory/BuzzFactoryTest.php
+++ b/tests/Unit/ClientFactory/BuzzFactoryTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Tests\Unit\ClientFactory;
 
 use Http\Adapter\Buzz\Client;
diff --git a/tests/Unit/ClientFactory/CurlFactoryTest.php b/tests/Unit/ClientFactory/CurlFactoryTest.php
index cb7c3dbc..7e4fa6a8 100644
--- a/tests/Unit/ClientFactory/CurlFactoryTest.php
+++ b/tests/Unit/ClientFactory/CurlFactoryTest.php
@@ -1,9 +1,11 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Tests\Unit\ClientFactory;
 
-use Http\HttplugBundle\ClientFactory\CurlFactory;
 use Http\Client\Curl\Client;
+use Http\HttplugBundle\ClientFactory\CurlFactory;
 use PHPUnit\Framework\TestCase;
 use Psr\Http\Message\ResponseFactoryInterface;
 use Psr\Http\Message\StreamFactoryInterface;
diff --git a/tests/Unit/ClientFactory/Guzzle6FactoryTest.php b/tests/Unit/ClientFactory/Guzzle6FactoryTest.php
index 0001712b..51307ac3 100644
--- a/tests/Unit/ClientFactory/Guzzle6FactoryTest.php
+++ b/tests/Unit/ClientFactory/Guzzle6FactoryTest.php
@@ -1,9 +1,11 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Tests\Unit\ClientFactory;
 
-use Http\HttplugBundle\ClientFactory\Guzzle6Factory;
 use Http\Adapter\Guzzle6\Client;
+use Http\HttplugBundle\ClientFactory\Guzzle6Factory;
 use PHPUnit\Framework\TestCase;
 
 /**
diff --git a/tests/Unit/ClientFactory/MockFactoryTest.php b/tests/Unit/ClientFactory/MockFactoryTest.php
index 362300db..1c8d243e 100644
--- a/tests/Unit/ClientFactory/MockFactoryTest.php
+++ b/tests/Unit/ClientFactory/MockFactoryTest.php
@@ -1,4 +1,6 @@
 <?php
+
+declare(strict_types=1);
 /**
  * This file is part of the HttplugBundle package.
  *
diff --git a/tests/Unit/ClientFactory/ReactFactoryTest.php b/tests/Unit/ClientFactory/ReactFactoryTest.php
index 311572f6..c31783b3 100644
--- a/tests/Unit/ClientFactory/ReactFactoryTest.php
+++ b/tests/Unit/ClientFactory/ReactFactoryTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Tests\Unit\ClientFactory;
 
 use Http\Adapter\React\Client;
diff --git a/tests/Unit/ClientFactory/SocketFactoryTest.php b/tests/Unit/ClientFactory/SocketFactoryTest.php
index 11b06efe..71e8cdc4 100644
--- a/tests/Unit/ClientFactory/SocketFactoryTest.php
+++ b/tests/Unit/ClientFactory/SocketFactoryTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Tests\Unit\ClientFactory;
 
 use Http\Client\Socket\Client;
diff --git a/tests/Unit/ClientFactory/SymfonyFactoryTest.php b/tests/Unit/ClientFactory/SymfonyFactoryTest.php
index f6b726cf..4fd29e43 100644
--- a/tests/Unit/ClientFactory/SymfonyFactoryTest.php
+++ b/tests/Unit/ClientFactory/SymfonyFactoryTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Tests\Unit\ClientFactory;
 
 use Http\HttplugBundle\ClientFactory\SymfonyFactory;
diff --git a/tests/Unit/Collector/CollectorTest.php b/tests/Unit/Collector/CollectorTest.php
index 708fe427..a4e0dd65 100644
--- a/tests/Unit/Collector/CollectorTest.php
+++ b/tests/Unit/Collector/CollectorTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Tests\Unit\Collector;
 
 use Http\HttplugBundle\Collector\Collector;
diff --git a/tests/Unit/Collector/FormatterTest.php b/tests/Unit/Collector/FormatterTest.php
index e1547ce4..2ea3247e 100644
--- a/tests/Unit/Collector/FormatterTest.php
+++ b/tests/Unit/Collector/FormatterTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Tests\Unit\Collector;
 
 use GuzzleHttp\Psr7\Request;
diff --git a/tests/Unit/Collector/PluginClientFactoryListenerTest.php b/tests/Unit/Collector/PluginClientFactoryListenerTest.php
index 54b60152..ef2be31a 100644
--- a/tests/Unit/Collector/PluginClientFactoryListenerTest.php
+++ b/tests/Unit/Collector/PluginClientFactoryListenerTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Tests\Unit\Collector;
 
 use Http\Client\Common\PluginClientFactory as DefaultPluginClientFactory;
diff --git a/tests/Unit/Collector/ProfileClientFactoryTest.php b/tests/Unit/Collector/ProfileClientFactoryTest.php
index 0aa9004d..4aeae247 100644
--- a/tests/Unit/Collector/ProfileClientFactoryTest.php
+++ b/tests/Unit/Collector/ProfileClientFactoryTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Tests\Unit\Collector;
 
 use Http\Client\HttpClient;
diff --git a/tests/Unit/Collector/ProfileClientTest.php b/tests/Unit/Collector/ProfileClientTest.php
index d9694bca..a6db587a 100644
--- a/tests/Unit/Collector/ProfileClientTest.php
+++ b/tests/Unit/Collector/ProfileClientTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Tests\Unit\Collector;
 
 use GuzzleHttp\Psr7\Request;
diff --git a/tests/Unit/Collector/ProfilePluginTest.php b/tests/Unit/Collector/ProfilePluginTest.php
index 2b396b9d..115d8c60 100644
--- a/tests/Unit/Collector/ProfilePluginTest.php
+++ b/tests/Unit/Collector/ProfilePluginTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Tests\Unit\Collector;
 
 use GuzzleHttp\Psr7\Request;
diff --git a/tests/Unit/Collector/StackPluginTest.php b/tests/Unit/Collector/StackPluginTest.php
index d9ac0eff..aebad53e 100644
--- a/tests/Unit/Collector/StackPluginTest.php
+++ b/tests/Unit/Collector/StackPluginTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Tests\Unit\Collector;
 
 use GuzzleHttp\Psr7\Request;
diff --git a/tests/Unit/DependencyInjection/ConfigurationTest.php b/tests/Unit/DependencyInjection/ConfigurationTest.php
index c773c797..31cabb8d 100644
--- a/tests/Unit/DependencyInjection/ConfigurationTest.php
+++ b/tests/Unit/DependencyInjection/ConfigurationTest.php
@@ -1,14 +1,16 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Tests\Unit\DependencyInjection;
 
+use Http\Adapter\Guzzle6\Client;
 use Http\HttplugBundle\DependencyInjection\Configuration;
 use Http\HttplugBundle\DependencyInjection\HttplugExtension;
-use Matthias\SymfonyDependencyInjectionTest\PhpUnit\AbstractExtensionConfigurationTestCase;
-use Http\Adapter\Guzzle6\Client;
 use Http\Message\MessageFactory\GuzzleMessageFactory;
-use Http\Message\UriFactory\GuzzleUriFactory;
 use Http\Message\StreamFactory\GuzzleStreamFactory;
+use Http\Message\UriFactory\GuzzleUriFactory;
+use Matthias\SymfonyDependencyInjectionTest\PhpUnit\AbstractExtensionConfigurationTestCase;
 use Nyholm\Psr7\Factory\Psr17Factory;
 use Symfony\Component\Config\Definition\ConfigurationInterface;
 use Symfony\Component\Config\Definition\Exception\InvalidConfigurationException;
diff --git a/tests/Unit/DependencyInjection/HttplugExtensionTest.php b/tests/Unit/DependencyInjection/HttplugExtensionTest.php
index d4b8731c..5d6e8ed2 100644
--- a/tests/Unit/DependencyInjection/HttplugExtensionTest.php
+++ b/tests/Unit/DependencyInjection/HttplugExtensionTest.php
@@ -1,7 +1,10 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Tests\Unit\DependencyInjection;
 
+use Http\Adapter\Guzzle6\Client;
 use Http\Client\HttpClient;
 use Http\Client\Plugin\Vcr\Recorder\InMemoryRecorder;
 use Http\HttplugBundle\Collector\PluginClientFactoryListener;
@@ -9,7 +12,6 @@
 use Matthias\SymfonyDependencyInjectionTest\PhpUnit\AbstractExtensionTestCase;
 use Symfony\Component\DependencyInjection\Reference;
 use Symfony\Component\HttpKernel\Kernel;
-use Http\Adapter\Guzzle6\Client;
 
 /**
  * @author David Buchmann <mail@davidbu.ch>
diff --git a/tests/Unit/Discovery/ConfiguredClientsStrategyTest.php b/tests/Unit/Discovery/ConfiguredClientsStrategyTest.php
index 2efeff12..ed3f44a7 100644
--- a/tests/Unit/Discovery/ConfiguredClientsStrategyTest.php
+++ b/tests/Unit/Discovery/ConfiguredClientsStrategyTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Http\HttplugBundle\Tests\Unit\Discovery;
 
 use Http\Client\HttpAsyncClient;