Add assert in test live component

src/LiveComponent/src/Test/InteractsWithLiveComponents.php

@@ -44,4 +44,24 @@ protected function createLiveComponent(string $name, array $data = [], ?KernelBr
             self::getContainer()->get('router'),
         );
     }
+
+    protected function assertComponentEmitEvent(TestLiveComponent $testLiveComponent, string $eventName, ?array $parameters = null): void
+    {
+        $eventData = $testLiveComponent->getEmittedEvent($testLiveComponent->render(), $eventName);
+
+        $this->assertNotNull($eventData, \sprintf('Event %s not emitted', $eventName));
+
+        if (null === $parameters) {
+            return;
+        }
+
+        foreach ($parameters as $key => $value) {
+            $this->assertSame($value, $eventData['data'][$key] ?? null, \sprintf('EventData (%s) is not valid', $key));
+        }
+    }
+
+    protected function assertComponentNotEmitEvent(TestLiveComponent $testLiveComponent, string $eventName): void
+    {
+        $this->assertNull($testLiveComponent->getEmittedEvent($testLiveComponent->render(), $eventName), \sprintf('Event %s emitted', $eventName));
+    }
 }

src/LiveComponent/src/Test/TestLiveComponent.php

@@ -229,4 +229,35 @@ private function flattenFormValues(array $values, string $prefix = ''): array
 
         return $result;
     }
+
+    /**
+     * @return ?array{data: array<string, string>, event: string}
+     */
+    public function getEmittedEvent(RenderedComponent $render, string $eventName): ?array
+    {
+        $eventsData = $this->getEmittedEvents($render);
+
+        foreach ($eventsData as $eventData) {
+            if ($eventData['event'] === $eventName) {
+                return $eventData;
+            }
+        }
+
+        return null;
+    }
+
+    /**
+     * @return array<int, array{data: array<string, string>, event: string}>
+     */
+    public function getEmittedEvents(RenderedComponent $render): array
+    {
+        $div = $render->crawler()->filter('[data-live-name-value]');
+        $emit = $div->attr('data-live-events-to-emit-value');
+
+        if (null === $emit) {
+            return [];
+        }
+
+        return json_decode($emit, true);
+    }
 }

src/LiveComponent/tests/Functional/Test/InteractsWithLiveComponentsTest.php

@@ -11,6 +11,7 @@
 
 namespace Symfony\UX\LiveComponent\Tests\Functional\Test;
 
+use PHPUnit\Framework\AssertionFailedError;
 use Symfony\Bundle\FrameworkBundle\Test\KernelTestCase;
 use Symfony\Component\Security\Core\Exception\AccessDeniedException;
 use Symfony\Component\Security\Core\User\InMemoryUser;
@@ -217,4 +218,38 @@ public function testSetLocaleRenderLocalizedComponent(): void
         $testComponent->setRouteLocale('de');
         $this->assertStringContainsString('Locale: de', $testComponent->render());
     }
+
+    public function testComponentEmitsExpectedEventWithParameters(): void
+    {
+        $testComponent = $this->createLiveComponent('component_with_emit');
+
+        $testComponent->call('actionThatEmits');
+
+        $this->assertComponentEmitEvent($testComponent, 'event1', [
+            'foo' => 'bar',
+        ]);
+    }
+
+    public function testComponentDoesNotEmitUnexpectedEvent(): void
+    {
+        $testComponent = $this->createLiveComponent('component_with_emit');
+
+        $testComponent->call('actionThatEmits');
+
+        $this->assertComponentNotEmitEvent($testComponent, 'non_emitted_event');
+    }
+
+    public function testComponentEmitsEventWithWrongParametersFails(): void
+    {
+        $testComponent = $this->createLiveComponent('component_with_emit');
+
+        $testComponent->call('actionThatEmits');
+
+        $this->expectException(AssertionFailedError::class);
+        $this->expectExceptionMessage('EventData (foo2) is not valid');
+        $this->assertComponentEmitEvent($testComponent, 'event1', [
+            'foo' => 'bar',
+            'foo2' => 'bar2',
+        ]);
+    }
 }