Add documentation

Author: Arkalo2

src/LiveComponent/doc/index.rst

@@ -3829,6 +3829,44 @@ uses Symfony's test client to render and make requests to your components::
     The ``InteractsWithLiveComponents`` trait can only be used in tests that extend
     ``Symfony\Bundle\FrameworkBundle\Test\KernelTestCase``.
 
+When testing live components, you can assert whether a specific event has been emitted using new assertion methods provided by the ``InteractsWithLiveComponents`` trait.
+
+Use the following assertions to verify event emissions from your live component::
+
+    use Symfony\Bundle\FrameworkBundle\Test\KernelTestCase;
+    use Symfony\UX\LiveComponent\Test\InteractsWithLiveComponents;
+
+    class MyComponentTest extends KernelTestCase
+    {
+        use InteractsWithLiveComponents;
+
+        public function testEventEmission(): void
+        {
+            $testComponent = $this->createLiveComponent(
+                name: 'MyComponent',
+                data: ['foo' => 'bar'],
+            );
+
+            // Call an action that emits an event
+            $render = $testComponent->call('triggerEvent')->render();
+
+            // Assert that the event was emitted with arguments
+            $this->componentHasEmittedEvent($render, 'event-name', [
+                'eventArg1' => 'value',
+            ]);
+
+            // Assert that a specific event was *not* emitted
+            $this->assertComponentNotEmitEvent($render, 'unwanted-event');
+        }
+    }
+
+.. note::
+
+    These assertions are only available when using the ``InteractsWithLiveComponents`` trait in a test class that extends
+    ``Symfony\Bundle\FrameworkBundle\Test\KernelTestCase``.
+
+---
+
 Test LiveCollectionType
 ~~~~~~~~~~~~~~~~~~~~~~~