diff --git a/src/Collector/Formatter.php b/src/Collector/Formatter.php
index 619d43bb..3ad1574c 100644
--- a/src/Collector/Formatter.php
+++ b/src/Collector/Formatter.php
@@ -4,11 +4,9 @@
 
 namespace Http\HttplugBundle\Collector;
 
-use Exception;
 use Http\Client\Exception\HttpException;
 use Http\Client\Exception\TransferException;
 use Http\Message\Formatter as MessageFormatter;
-use Http\Message\Formatter\CurlCommandFormatter;
 use Psr\Http\Client\NetworkExceptionInterface;
 use Psr\Http\Message\RequestInterface;
 use Psr\Http\Message\ResponseInterface;
@@ -29,11 +27,11 @@ final class Formatter implements MessageFormatter
     private $formatter;
 
     /**
-     * @var CurlCommandFormatter
+     * @var MessageFormatter
      */
     private $curlFormatter;
 
-    public function __construct(MessageFormatter $formatter, CurlCommandFormatter $curlFormatter)
+    public function __construct(MessageFormatter $formatter, MessageFormatter $curlFormatter)
     {
         $this->formatter = $formatter;
         $this->curlFormatter = $curlFormatter;
diff --git a/tests/Unit/Collector/PluginClientFactoryListenerTest.php b/tests/Unit/Collector/PluginClientFactoryListenerTest.php
index ef2be31a..376d317e 100644
--- a/tests/Unit/Collector/PluginClientFactoryListenerTest.php
+++ b/tests/Unit/Collector/PluginClientFactoryListenerTest.php
@@ -9,6 +9,7 @@
 use Http\HttplugBundle\Collector\Formatter;
 use Http\HttplugBundle\Collector\PluginClientFactory;
 use Http\HttplugBundle\Collector\PluginClientFactoryListener;
+use Http\Message\Formatter as MessageFormatter;
 use Nyholm\NSA;
 use PHPUnit\Framework\TestCase;
 use Symfony\Component\EventDispatcher\Event as LegacyEvent;
@@ -20,9 +21,9 @@ final class PluginClientFactoryListenerTest extends TestCase
 {
     public function testRegisterPluginClientFactory(): void
     {
-        $collector = $this->getMockBuilder(Collector::class)->getMock();
-        $formatter = $this->getMockBuilder(Formatter::class)->disableOriginalConstructor()->getMock();
-        $stopwatch = $this->getMockBuilder(Stopwatch::class)->getMock();
+        $collector = new Collector();
+        $formatter = new Formatter($this->createMock(MessageFormatter::class), $this->createMock(MessageFormatter::class));
+        $stopwatch = $this->createMock(Stopwatch::class);
 
         $factory = new PluginClientFactory($collector, $formatter, $stopwatch);
 
diff --git a/tests/Unit/Collector/ProfileClientFactoryTest.php b/tests/Unit/Collector/ProfileClientFactoryTest.php
index 4aeae247..0b893423 100644
--- a/tests/Unit/Collector/ProfileClientFactoryTest.php
+++ b/tests/Unit/Collector/ProfileClientFactoryTest.php
@@ -10,6 +10,7 @@
 use Http\HttplugBundle\Collector\Formatter;
 use Http\HttplugBundle\Collector\ProfileClient;
 use Http\HttplugBundle\Collector\ProfileClientFactory;
+use Http\Message\Formatter as MessageFormatter;
 use PHPUnit\Framework\TestCase;
 use Symfony\Component\Stopwatch\Stopwatch;
 
@@ -37,10 +38,10 @@ class ProfileClientFactoryTest extends TestCase
 
     public function setUp(): void
     {
-        $this->collector = $this->getMockBuilder(Collector::class)->disableOriginalConstructor()->getMock();
-        $this->formatter = $this->getMockBuilder(Formatter::class)->disableOriginalConstructor()->getMock();
-        $this->stopwatch = $this->getMockBuilder(Stopwatch::class)->getMock();
-        $this->client = $this->getMockBuilder(HttpClient::class)->getMock();
+        $this->collector = new Collector();
+        $this->formatter = new Formatter($this->createMock(MessageFormatter::class), $this->createMock(MessageFormatter::class));
+        $this->stopwatch = $this->createMock(Stopwatch::class);
+        $this->client = $this->createMock(HttpClient::class);
     }
 
     public function testCreateClientFromClientFactory(): void
diff --git a/tests/Unit/Collector/ProfileClientTest.php b/tests/Unit/Collector/ProfileClientTest.php
index a6db587a..c8fb9501 100644
--- a/tests/Unit/Collector/ProfileClientTest.php
+++ b/tests/Unit/Collector/ProfileClientTest.php
@@ -13,6 +13,7 @@
 use Http\HttplugBundle\Collector\Formatter;
 use Http\HttplugBundle\Collector\ProfileClient;
 use Http\HttplugBundle\Collector\Stack;
+use Http\Message\Formatter as MessageFormatter;
 use Http\Promise\FulfilledPromise;
 use Http\Promise\Promise;
 use Http\Promise\RejectedPromise;
@@ -47,7 +48,7 @@ class ProfileClientTest extends TestCase
     private $request;
 
     /**
-     * @var Formatter|MockObject
+     * @var Formatter
      */
     private $formatter;
 
@@ -93,22 +94,23 @@ class ProfileClientTest extends TestCase
 
     public function setUp(): void
     {
-        $this->collector = $this->getMockBuilder(Collector::class)->disableOriginalConstructor()->getMock();
+        $messageFormatter = $this->createMock(MessageFormatter::class);
+        $this->formatter = new Formatter($messageFormatter, $this->createMock(MessageFormatter::class));
+        $this->collector = new Collector();
+        $this->stopwatch = $this->createMock(Stopwatch::class);
+
         $this->activeStack = new Stack('default', 'FormattedRequest');
         $this->client = $this->getMockBuilder(ClientInterface::class)->getMock();
         $this->uri = new Uri('https://example.com/target');
         $this->request = new Request('GET', $this->uri);
-        $this->formatter = $this->getMockBuilder(Formatter::class)->disableOriginalConstructor()->getMock();
-        $this->stopwatch = $this->getMockBuilder(Stopwatch::class)->disableOriginalConstructor()->getMock();
-        $this->stopwatchEvent = $this->getMockBuilder(StopwatchEvent::class)->disableOriginalConstructor()->getMock();
+        $this->stopwatchEvent = $this->createMock(StopwatchEvent::class);
         $this->subject = new ProfileClient($this->client, $this->collector, $this->formatter, $this->stopwatch);
         $this->response = new Response();
         $this->exception = new \Exception();
         $this->fulfilledPromise = new FulfilledPromise($this->response);
         $this->rejectedPromise = new RejectedPromise($this->exception);
 
-        $this->collector->method('getActiveStack')->willReturn($this->activeStack);
-        $this->formatter
+        $messageFormatter
             ->method('formatResponse')
             ->with($this->response)
             ->willReturn('FormattedResponse')
@@ -151,10 +153,6 @@ public function testSendRequestTypeError()
             ->willReturnCallback(function () {
                 throw new \Error('You set string to int prop');
             });
-        $this->formatter
-            ->expects($this->once())
-            ->method('formatException')
-            ->with($this->isInstanceOf(\Error::class));
 
         $this->expectException(\Error::class);
         $this->expectExceptionMessage('You set string to int prop');
@@ -170,11 +168,6 @@ public function testSendAsyncRequest(): void
             ->willReturn($this->fulfilledPromise)
         ;
 
-        $this->collector
-            ->expects($this->once())
-            ->method('deactivateStack')
-        ;
-
         $promise = $this->subject->sendAsyncRequest($this->request);
 
         $this->assertEquals($this->fulfilledPromise, $promise);
@@ -186,12 +179,6 @@ public function testSendAsyncRequest(): void
 
     public function testOnFulfilled(): void
     {
-        $this->collector
-            ->expects($this->once())
-            ->method('activateStack')
-            ->with($this->activeStack)
-        ;
-
         $this->stopwatchEvent
             ->expects($this->once())
             ->method('stop')
@@ -211,12 +198,6 @@ public function testOnFulfilled(): void
 
     public function testOnRejected(): void
     {
-        $this->collector
-            ->expects($this->once())
-            ->method('activateStack')
-            ->with($this->activeStack)
-        ;
-
         $this->stopwatchEvent
             ->expects($this->once())
             ->method('stop')
@@ -227,16 +208,10 @@ public function testOnRejected(): void
             ->willReturn($this->rejectedPromise)
         ;
 
-        $this->formatter
-            ->method('formatException')
-            ->with($this->exception)
-            ->willReturn('FormattedException')
-        ;
-
         $this->subject->sendAsyncRequest($this->request);
 
         $this->assertEquals(42, $this->activeStack->getDuration());
-        $this->assertEquals('FormattedException', $this->activeStack->getClientException());
+        $this->assertEquals('FormattedResponse', $this->activeStack->getClientException());
     }
 }
 
diff --git a/tests/Unit/Collector/ProfilePluginTest.php b/tests/Unit/Collector/ProfilePluginTest.php
index 115d8c60..12d74e4f 100644
--- a/tests/Unit/Collector/ProfilePluginTest.php
+++ b/tests/Unit/Collector/ProfilePluginTest.php
@@ -12,9 +12,11 @@
 use Http\HttplugBundle\Collector\Formatter;
 use Http\HttplugBundle\Collector\ProfilePlugin;
 use Http\HttplugBundle\Collector\Stack;
+use Http\Message\Formatter as MessageFormatter;
 use Http\Promise\FulfilledPromise;
 use Http\Promise\Promise;
 use Http\Promise\RejectedPromise;
+use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
 use Psr\Http\Message\RequestInterface;
 use Psr\Http\Message\ResponseInterface;
@@ -22,7 +24,7 @@
 class ProfilePluginTest extends TestCase
 {
     /**
-     * @var Plugin
+     * @var Plugin|MockObject
      */
     private $plugin;
 
@@ -73,20 +75,17 @@ class ProfilePluginTest extends TestCase
 
     public function setUp(): void
     {
+        $this->collector = new Collector();
+        $messageFormatter = $this->createMock(MessageFormatter::class);
+        $this->formatter = new Formatter($messageFormatter, $this->createMock(MessageFormatter::class));
+
         $this->plugin = $this->getMockBuilder(Plugin::class)->getMock();
-        $this->collector = $this->getMockBuilder(Collector::class)->disableOriginalConstructor()->getMock();
         $this->request = new Request('GET', '/');
         $this->response = new Response();
         $this->fulfilledPromise = new FulfilledPromise($this->response);
         $this->currentStack = new Stack('default', 'FormattedRequest');
         $this->exception = new TransferException();
         $this->rejectedPromise = new RejectedPromise($this->exception);
-        $this->formatter = $this->getMockBuilder(Formatter::class)->disableOriginalConstructor()->getMock();
-
-        $this->collector
-            ->method('getActiveStack')
-            ->willReturn($this->currentStack)
-        ;
 
         $this->plugin
             ->method('handleRequest')
@@ -95,29 +94,22 @@ public function setUp(): void
             })
         ;
 
-        $this->formatter
+        $messageFormatter
             ->method('formatRequest')
             ->with($this->identicalTo($this->request))
             ->willReturn('FormattedRequest')
         ;
 
-        $this->formatter
+        $messageFormatter
             ->method('formatResponse')
             ->with($this->identicalTo($this->response))
             ->willReturn('FormattedResponse')
         ;
 
-        $this->formatter
-            ->method('formatException')
-            ->with($this->identicalTo($this->exception))
-            ->willReturn('FormattedException')
-        ;
-
         $this->subject = new ProfilePlugin(
             $this->plugin,
             $this->collector,
-            $this->formatter,
-            'http.plugin.mock'
+            $this->formatter
         );
     }
 
@@ -177,7 +169,9 @@ public function testOnRejected(): void
         }, function (): void {
         });
 
+        $this->assertEquals($this->exception, $promise->wait());
+        $profile = $this->currentStack->getProfiles()[0];
         $this->expectException(TransferException::class);
-        $promise->wait();
+        $profile->getResponse();
     }
 }
diff --git a/tests/Unit/Collector/StackPluginTest.php b/tests/Unit/Collector/StackPluginTest.php
index 8eb443cd..ddb5f2cb 100644
--- a/tests/Unit/Collector/StackPluginTest.php
+++ b/tests/Unit/Collector/StackPluginTest.php
@@ -9,8 +9,8 @@
 use Http\Client\Exception\HttpException;
 use Http\HttplugBundle\Collector\Collector;
 use Http\HttplugBundle\Collector\Formatter;
-use Http\HttplugBundle\Collector\Stack;
 use Http\HttplugBundle\Collector\StackPlugin;
+use Http\Message\Formatter as MessageFormatter;
 use Http\Promise\FulfilledPromise;
 use Http\Promise\RejectedPromise;
 use PHPUnit\Framework\Error\Warning;
@@ -52,75 +52,43 @@ class StackPluginTest extends TestCase
 
     public function setUp(): void
     {
-        $this->collector = $this->getMockBuilder(Collector::class)->disableOriginalConstructor()->getMock();
-        $this->formatter = $this->getMockBuilder(Formatter::class)->disableOriginalConstructor()->getMock();
+        $this->collector = new Collector();
+        $messageFormatter = $this->createMock(MessageFormatter::class);
+        $this->formatter = new Formatter($messageFormatter, $this->createMock(MessageFormatter::class));
         $this->request = new Request('GET', '/');
         $this->response = new Response();
         $this->exception = new HttpException('', $this->request, $this->response);
 
-        $this->formatter
+        $messageFormatter
             ->method('formatRequest')
             ->with($this->request)
             ->willReturn('FormattedRequest')
         ;
 
-        $this->formatter
+        $messageFormatter
             ->method('formatResponse')
             ->with($this->response)
             ->willReturn('FormattedResponse')
         ;
 
-        $this->formatter
-            ->method('formatException')
-            ->with($this->exception)
-            ->willReturn('FormattedException')
-        ;
-
         $this->subject = new StackPlugin($this->collector, $this->formatter, 'default');
     }
 
     public function testStackIsInitialized(): void
     {
-        $this->collector
-            ->expects($this->once())
-            ->method('addStack')
-            ->with($this->callback(function (Stack $stack) {
-                $this->assertEquals('default', $stack->getClient());
-                $this->assertEquals('FormattedRequest', $stack->getRequest());
-
-                return true;
-            }))
-        ;
-        $this->collector
-            ->expects($this->once())
-            ->method('activateStack')
-        ;
-
         $next = function () {
             return new FulfilledPromise($this->response);
         };
 
         $this->subject->handleRequest($this->request, $next, function (): void {
         });
+        $stack = $this->collector->getActiveStack();
+        $this->assertEquals('default', $stack->getClient());
+        $this->assertEquals('FormattedRequest', $stack->getRequest());
     }
 
     public function testOnFulfilled(): void
     {
-        //Capture the current stack
-        $currentStack = null;
-        $this->collector
-            ->method('addStack')
-            ->with($this->callback(function (Stack $stack) use (&$currentStack) {
-                $currentStack = $stack;
-
-                return true;
-            }))
-        ;
-        $this->collector
-            ->expects($this->once())
-            ->method('deactivateStack')
-        ;
-
         $next = function () {
             return new FulfilledPromise($this->response);
         };
@@ -129,27 +97,12 @@ public function testOnFulfilled(): void
         });
 
         $this->assertEquals($this->response, $promise->wait());
-        $this->assertInstanceOf(Stack::class, $currentStack);
+        $currentStack = $this->collector->getActiveStack();
         $this->assertEquals('FormattedResponse', $currentStack->getResponse());
     }
 
     public function testOnRejected(): void
     {
-        //Capture the current stack
-        $currentStack = null;
-        $this->collector
-            ->method('addStack')
-            ->with($this->callback(function (Stack $stack) use (&$currentStack) {
-                $currentStack = $stack;
-
-                return true;
-            }))
-        ;
-        $this->collector
-            ->expects($this->once())
-            ->method('deactivateStack')
-        ;
-
         $next = function () {
             return new RejectedPromise($this->exception);
         };
@@ -157,17 +110,14 @@ public function testOnRejected(): void
         $promise = $this->subject->handleRequest($this->request, $next, function (): void {
         });
 
-        $this->expectException(\Exception::class);
-        $promise->wait();
+        $this->assertEquals($this->exception, $promise->wait());
+        $currentStack = $this->collector->getActiveStack();
+        $this->assertEquals('FormattedResponse', $currentStack->getResponse());
+        $this->assertTrue($currentStack->isFailed());
     }
 
     public function testOnException(): void
     {
-        $this->collector
-            ->expects($this->once())
-            ->method('deactivateStack')
-        ;
-
         $next = function (): void {
             throw new \Exception();
         };
@@ -185,11 +135,6 @@ public function testOnError(): void
             $this->expectException(Warning::class);
         }
 
-        $this->collector
-            ->expects($this->once())
-            ->method('deactivateStack')
-        ;
-
         $next = function () {
             return 2 / 0;
         };