Add TransitionListener and add test

src/Dispatcher/AbstractSubject.php

@@ -5,6 +5,7 @@
 namespace DDDPHP\StateMachine\Dispatcher;
 
 use DDDPHP\StateMachine\Event\EventInterface;
+use DDDPHP\StateMachine\StateMachine\StateMachineException;
 use Psr\EventDispatcher\EventDispatcherInterface;
 use Psr\EventDispatcher\ListenerProviderInterface;
 
@@ -20,7 +21,11 @@ public function __construct()
     }
     public function addListener(EventInterface $event, callable $listener): void
     {
-        $this->listeners[$event::class][] = $listener;
+        $classImplements = array_values(class_implements($event));
+        if (empty($classImplements[0])) {
+            throw new StateMachineException(" the event must implements an interface");
+        }
+        $this->listeners[$classImplements[0]][] = $listener;
     }
 
     public function fireEvent(EventInterface $event): void

src/Dispatcher/Dispatcher.php

@@ -16,9 +16,7 @@
 final class Dispatcher implements EventDispatcherInterface
 {
     private ListenerProviderInterface $listenerProvider;
-    /**
-     * @param ListenerProviderInterface $listenerProvider
-     */
+
     public function __construct(ListenerProviderInterface $listenerProvider)
     {
         $this->listenerProvider = $listenerProvider;

src/StateMachine/StateMachineImpl.php

@@ -119,4 +119,20 @@ public function setReady(bool $ready): void
     {
         $this->ready = $ready;
     }
+
+    public function addTransitionPreListener(callable $listener): void
+    {
+        $this->addListener(
+            new class () implements PreTransitionEventInterface {},
+            $listener
+        );
+    }
+
+    public function addTransitionPostListener(callable $listener): void
+    {
+        $this->addListener(
+            new class () implements PostTransitionEventInterface {},
+            $listener
+        );
+    }
 }

src/StateMachine/StateMachineInterface.php

@@ -15,4 +15,8 @@ public function fire(string $sourceStateId, string $event, $context): string;
     public function getMachineId(): string;
 
     public function showStateMachine(): void;
+
+    public function addTransitionPreListener(callable $listener): void;
+
+    public function addTransitionPostListener(callable $listener): void;
 }

tests/StateMachineTest.php

@@ -7,6 +7,7 @@
 use DDDPHP\StateMachine\Action\ActionInterface;
 use DDDPHP\StateMachine\Builder\StateMachineBuilderFactory;
 use DDDPHP\StateMachine\Condition\ConditionInterface;
+use DDDPHP\StateMachine\Event\PreTransitionEventInterface;
 use DDDPHP\StateMachine\StateMachine\StateMachineInterface;
 use PHPUnit\Framework\TestCase;
 
@@ -87,6 +88,31 @@ public function testInternalNormal(): void
         $this->assertEquals(self::STATE1, $target);
     }
 
+    public function testTransitionListener() :void
+    {
+        $preTransitionListenerCount = 0;
+        $postTransitionListenerCount = 0;
+        $builder = StateMachineBuilderFactory::create();
+        $builder->externalTransitions()
+            ->fromAmong(self::STATE1, self::STATE2, self::STATE3)
+            ->to(self::STATE4)
+            ->on(self::EVENT1)
+            ->when($this->checkCondition())
+            ->perform($this->doAction());
+        $stateMachine = $builder->build(self::MACHINE_ID . "transition-listener");
+
+        $stateMachine->addTransitionPreListener(function () use (&$preTransitionListenerCount) {
+            $preTransitionListenerCount += 1;
+        });
+        $stateMachine->addTransitionPostListener(function () use (&$postTransitionListenerCount) {
+            $postTransitionListenerCount += 2;
+        });
+
+        $stateMachine->fire(self::STATE2, self::EVENT1, $this->context);
+
+        $this->assertEquals(1, $preTransitionListenerCount);
+        $this->assertEquals(2, $postTransitionListenerCount);
+    }
     public function testExternalInternalNormal(): void
     {
         $stateMachine = $this->buildStateMachine();