diff --git a/src/Component/spec/StateMachine/OperationStateMachineSpec.php b/src/Component/spec/StateMachine/OperationStateMachineSpec.php
deleted file mode 100644
index 2998dceba..000000000
--- a/src/Component/spec/StateMachine/OperationStateMachineSpec.php
+++ /dev/null
@@ -1,101 +0,0 @@
-<?php
-
-/*
- * This file is part of the Sylius package.
- *
- * (c) Sylius Sp. z o.o.
- *
- * For the full copyright and license information, please view the LICENSE
- * file that was distributed with this source code.
- */
-
-declare(strict_types=1);
-
-namespace spec\Sylius\Resource\StateMachine;
-
-use PhpSpec\ObjectBehavior;
-use Psr\Container\ContainerInterface;
-use Sylius\Resource\Context\Context;
-use Sylius\Resource\Metadata\Create;
-use Sylius\Resource\Metadata\Index;
-use Sylius\Resource\Metadata\StateMachineAwareOperationInterface;
-use Sylius\Resource\StateMachine\OperationStateMachine;
-use Sylius\Resource\StateMachine\OperationStateMachineInterface;
-
-final class OperationStateMachineSpec extends ObjectBehavior
-{
-    function let(ContainerInterface $locator): void
-    {
-        $this->beConstructedWith($locator);
-    }
-
-    function it_is_initializable(): void
-    {
-        $this->shouldHaveType(OperationStateMachine::class);
-    }
-
-    function it_calls_can_method_from_operation_state_machine_as_string(
-        ContainerInterface $locator,
-        OperationStateMachineInterface $stateMachine,
-        \stdClass $data,
-    ): void {
-        $operation = (new Create())->withStateMachineComponent('symfony');
-        $context = new Context();
-
-        $locator->has('symfony')->willReturn(true);
-        $locator->get('symfony')->willReturn($stateMachine);
-
-        $stateMachine->can($data, $operation, $context)->willReturn(true)->shouldBeCalled();
-
-        $this->can($data, $operation, $context)->shouldReturn(true);
-    }
-
-    function it_returns_false_if_no_operation_state_machine_has_been_configured_on_operation(
-        ContainerInterface $locator,
-        OperationStateMachineInterface $stateMachine,
-        \stdClass $data,
-    ): void {
-        $operation = new Create();
-        $context = new Context();
-
-        $locator->has('\App\StateMachine')->willReturn(false);
-
-        $this->can($data, $operation, $context)->shouldReturn(false);
-    }
-
-    function it_calls_apply_method_from_operation_state_machine_as_string(
-        ContainerInterface $locator,
-        OperationStateMachineInterface $stateMachine,
-        \stdClass $data,
-    ): void {
-        $operation = (new Create())->withStateMachineComponent('symfony');
-        $context = new Context();
-
-        $locator->has('symfony')->willReturn(true);
-        $locator->get('symfony')->willReturn($stateMachine);
-
-        $stateMachine->apply($data, $operation, $context)->shouldBeCalled();
-
-        $this->apply($data, $operation, $context);
-    }
-
-    function it_does_nothing_if_no_operation_state_machine_has_been_configured_on_operation(
-        ContainerInterface $locator,
-        \stdClass $data,
-    ): void {
-        $operation = new Create();
-        $context = new Context();
-
-        $this->apply($data, $operation, $context);
-    }
-
-    function it_throws_an_exception_when_operation_does_not_implement_a_state_machine(
-        \stdClass $data,
-    ): void {
-        $operation = new Index();
-
-        $this->shouldThrow(
-            new \LogicException(sprintf('Expected an instance of %s. Got: %s', StateMachineAwareOperationInterface::class, Index::class)),
-        )->during('can', [$data, $operation, new Context()]);
-    }
-}
diff --git a/src/Component/spec/StateMachine/State/ApplyStateMachineTransitionProcessorSpec.php b/src/Component/spec/StateMachine/State/ApplyStateMachineTransitionProcessorSpec.php
deleted file mode 100644
index 4e1b2f0ca..000000000
--- a/src/Component/spec/StateMachine/State/ApplyStateMachineTransitionProcessorSpec.php
+++ /dev/null
@@ -1,70 +0,0 @@
-<?php
-
-/*
- * This file is part of the Sylius package.
- *
- * (c) Sylius Sp. z o.o.
- *
- * For the full copyright and license information, please view the LICENSE
- * file that was distributed with this source code.
- */
-
-declare(strict_types=1);
-
-namespace spec\Sylius\Resource\StateMachine\State;
-
-use PhpSpec\ObjectBehavior;
-use Sylius\Resource\Context\Context;
-use Sylius\Resource\Metadata\Create;
-use Sylius\Resource\State\ProcessorInterface;
-use Sylius\Resource\StateMachine\OperationStateMachineInterface;
-use Sylius\Resource\StateMachine\State\ApplyStateMachineTransitionProcessor;
-
-final class ApplyStateMachineTransitionProcessorSpec extends ObjectBehavior
-{
-    function let(
-        OperationStateMachineInterface $operationStateMachine,
-        ProcessorInterface $writeProcessor,
-    ): void {
-        $this->beConstructedWith($operationStateMachine, $writeProcessor);
-    }
-
-    function it_is_initializable(): void
-    {
-        $this->shouldHaveType(ApplyStateMachineTransitionProcessor::class);
-    }
-
-    function it_applies_state_machine_transition_if_possible(
-        \stdClass $data,
-        OperationStateMachineInterface $operationStateMachine,
-        ProcessorInterface $writeProcessor,
-    ): void {
-        $operation = new Create();
-
-        $context = new Context();
-
-        $operationStateMachine->can($data, $operation, $context)->willReturn(true)->shouldBeCalled();
-        $operationStateMachine->apply($data, $operation, $context)->shouldBeCalled();
-
-        $writeProcessor->process($data, $operation, $context)->willReturn(null)->shouldBeCalled();
-
-        $this->process($data, $operation, $context);
-    }
-
-    function it_does_nothing_when_transition_is_not_possible(
-        \stdClass $data,
-        OperationStateMachineInterface $operationStateMachine,
-        ProcessorInterface $writeProcessor,
-    ): void {
-        $operation = new Create();
-
-        $context = new Context();
-
-        $operationStateMachine->can($data, $operation, $context)->willReturn(false)->shouldBeCalled();
-        $operationStateMachine->apply($data, $operation, $context)->shouldNotBeCalled();
-
-        $writeProcessor->process($data, $operation, $context)->willReturn(null)->shouldBeCalled();
-
-        $this->process($data, $operation, $context)->shouldReturn(null);
-    }
-}
diff --git a/src/Component/tests/StateMachine/OperationStateMachineTest.php b/src/Component/tests/StateMachine/OperationStateMachineTest.php
new file mode 100644
index 000000000..b6be2aaad
--- /dev/null
+++ b/src/Component/tests/StateMachine/OperationStateMachineTest.php
@@ -0,0 +1,121 @@
+<?php
+
+/*
+ * This file is part of the Sylius package.
+ *
+ * (c) Sylius Sp. z o.o.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace Sylius\Resource\Tests\StateMachine;
+
+use LogicException;
+use PHPUnit\Framework\TestCase;
+use Psr\Container\ContainerInterface;
+use Sylius\Resource\Context\Context;
+use Sylius\Resource\Metadata\Create;
+use Sylius\Resource\Metadata\Index;
+use Sylius\Resource\Metadata\StateMachineAwareOperationInterface;
+use Sylius\Resource\StateMachine\OperationStateMachine;
+use Sylius\Resource\StateMachine\OperationStateMachineInterface;
+
+final class OperationStateMachineTest extends TestCase
+{
+    private ContainerInterface $locator;
+
+    private OperationStateMachine $operationStateMachine;
+
+    protected function setUp(): void
+    {
+        $this->locator = $this->createMock(ContainerInterface::class);
+        $this->operationStateMachine = new OperationStateMachine($this->locator);
+    }
+
+    public function testItIsInitializable(): void
+    {
+        $this->assertInstanceOf(OperationStateMachine::class, $this->operationStateMachine);
+    }
+
+    public function testItCallsCanMethodFromOperationStateMachineAsString(): void
+    {
+        $stateMachine = $this->createMock(OperationStateMachineInterface::class);
+        $data = new \stdClass();
+        $operation = (new Create())->withStateMachineComponent('symfony');
+        $context = new Context();
+
+        $this->locator->expects($this->once())
+            ->method('has')
+            ->with('symfony')
+            ->willReturn(true);
+
+        $this->locator->expects($this->once())
+            ->method('get')
+            ->with('symfony')
+            ->willReturn($stateMachine);
+
+        $stateMachine->expects($this->once())
+            ->method('can')
+            ->with($data, $operation, $context)
+            ->willReturn(true);
+
+        $this->assertTrue($this->operationStateMachine->can($data, $operation, $context));
+    }
+
+    public function testItReturnsFalseIfNoOperationStateMachineHasBeenConfiguredOnOperation(): void
+    {
+        $data = new \stdClass();
+        $operation = new Create();
+        $context = new Context();
+
+        $this->assertFalse($this->operationStateMachine->can($data, $operation, $context));
+    }
+
+    public function testItCallsApplyMethodFromOperationStateMachineAsString(): void
+    {
+        $stateMachine = $this->createMock(OperationStateMachineInterface::class);
+        $data = new \stdClass();
+        $operation = (new Create())->withStateMachineComponent('symfony');
+        $context = new Context();
+
+        $this->locator->expects($this->once())
+            ->method('has')
+            ->with('symfony')
+            ->willReturn(true);
+
+        $this->locator->expects($this->once())
+            ->method('get')
+            ->with('symfony')
+            ->willReturn($stateMachine);
+
+        $stateMachine->expects($this->once())
+            ->method('apply')
+            ->with($data, $operation, $context);
+
+        $this->operationStateMachine->apply($data, $operation, $context);
+    }
+
+    public function testItDoesNothingIfNoOperationStateMachineHasBeenConfiguredOnOperation(): void
+    {
+        $data = new \stdClass();
+        $operation = new Create();
+        $context = new Context();
+
+        $this->operationStateMachine->apply($data, $operation, $context);
+        $this->expectNotToPerformAssertions();
+    }
+
+    public function testItThrowsAnExceptionWhenOperationDoesNotImplementAStateMachine(): void
+    {
+        $data = new \stdClass();
+        $operation = new Index();
+
+        $this->expectException(LogicException::class);
+        $this->expectExceptionMessage(sprintf('Expected an instance of %s. Got: %s', StateMachineAwareOperationInterface::class, Index::class));
+
+        $this->operationStateMachine->can($data, $operation, new Context());
+    }
+}
diff --git a/src/Component/tests/StateMachine/State/ApplyStateMachineTransitionProcessorSpec.php b/src/Component/tests/StateMachine/State/ApplyStateMachineTransitionProcessorSpec.php
new file mode 100644
index 000000000..25a2ba564
--- /dev/null
+++ b/src/Component/tests/StateMachine/State/ApplyStateMachineTransitionProcessorSpec.php
@@ -0,0 +1,90 @@
+<?php
+
+/*
+ * This file is part of the Sylius package.
+ *
+ * (c) Sylius Sp. z o.o.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace Sylius\Resource\Tests\StateMachine\State;
+
+use PHPUnit\Framework\TestCase;
+use Sylius\Resource\Context\Context;
+use Sylius\Resource\Metadata\Create;
+use Sylius\Resource\State\ProcessorInterface;
+use Sylius\Resource\StateMachine\OperationStateMachineInterface;
+use Sylius\Resource\StateMachine\State\ApplyStateMachineTransitionProcessor;
+
+final class ApplyStateMachineTransitionProcessorTest extends TestCase
+{
+    private OperationStateMachineInterface $operationStateMachine;
+
+    private ProcessorInterface $writeProcessor;
+
+    private ApplyStateMachineTransitionProcessor $processor;
+
+    protected function setUp(): void
+    {
+        $this->operationStateMachine = $this->createMock(OperationStateMachineInterface::class);
+        $this->writeProcessor = $this->createMock(ProcessorInterface::class);
+        $this->processor = new ApplyStateMachineTransitionProcessor(
+            $this->operationStateMachine,
+            $this->writeProcessor,
+        );
+    }
+
+    public function testItIsInitializable(): void
+    {
+        $this->assertInstanceOf(ApplyStateMachineTransitionProcessor::class, $this->processor);
+    }
+
+    public function testItAppliesStateMachineTransitionIfPossible(): void
+    {
+        $data = new \stdClass();
+        $operation = new Create();
+        $context = new Context();
+
+        $this->operationStateMachine->expects($this->once())
+            ->method('can')
+            ->with($data, $operation, $context)
+            ->willReturn(true);
+
+        $this->operationStateMachine->expects($this->once())
+            ->method('apply')
+            ->with($data, $operation, $context);
+
+        $this->writeProcessor->expects($this->once())
+            ->method('process')
+            ->with($data, $operation, $context)
+            ->willReturn(null);
+
+        $this->processor->process($data, $operation, $context);
+    }
+
+    public function testItDoesNothingWhenTransitionIsNotPossible(): void
+    {
+        $data = new \stdClass();
+        $operation = new Create();
+        $context = new Context();
+
+        $this->operationStateMachine->expects($this->once())
+            ->method('can')
+            ->with($data, $operation, $context)
+            ->willReturn(false);
+
+        $this->operationStateMachine->expects($this->never())
+            ->method('apply');
+
+        $this->writeProcessor->expects($this->once())
+            ->method('process')
+            ->with($data, $operation, $context)
+            ->willReturn(null);
+
+        $this->assertNull($this->processor->process($data, $operation, $context));
+    }
+}
diff --git a/src/Component/spec/StateMachine/StateMachineSpec.php b/src/Component/tests/StateMachine/StateMachineTest.php
similarity index 52%
rename from src/Component/spec/StateMachine/StateMachineSpec.php
rename to src/Component/tests/StateMachine/StateMachineTest.php
index d17dd4804..af7d415b0 100644
--- a/src/Component/spec/StateMachine/StateMachineSpec.php
+++ b/src/Component/tests/StateMachine/StateMachineTest.php
@@ -11,17 +11,19 @@
 
 declare(strict_types=1);
 
-namespace spec\Sylius\Resource\StateMachine;
+namespace Sylius\Resource\Tests\StateMachine;
 
-use PhpSpec\ObjectBehavior;
+use PHPUnit\Framework\TestCase;
 use Sylius\Resource\StateMachine\StateMachine;
 use Sylius\Resource\Tests\Dummy\PullRequest;
 
-final class StateMachineSpec extends ObjectBehavior
+final class StateMachineTest extends TestCase
 {
-    function let(): void
+    private StateMachine $stateMachine;
+
+    protected function setUp(): void
     {
-        $this->beConstructedWith(new PullRequest(), [
+        $this->stateMachine = new StateMachine(new PullRequest(), [
             'graph' => 'pull_request',
             'property_path' => 'currentPlace',
             'places' => [
@@ -37,18 +39,18 @@ function let(): void
         ]);
     }
 
-    function it_is_initializable(): void
+    public function testItIsInitializable(): void
     {
-        $this->shouldHaveType(StateMachine::class);
+        $this->assertInstanceOf(StateMachine::class, $this->stateMachine);
     }
 
-    function it_gets_transition_from_a_state(): void
+    public function testItGetsTransitionFromAState(): void
     {
-        $this->getTransitionFromState('start')->shouldReturn('submit');
+        $this->assertSame('submit', $this->stateMachine->getTransitionFromState('start'));
     }
 
-    function it_gets_transition_to_a_state(): void
+    public function testItGetsTransitionToAState(): void
     {
-        $this->getTransitionToState('test')->shouldReturn('submit');
+        $this->assertSame('submit', $this->stateMachine->getTransitionToState('test'));
     }
 }