✅(y-webrtc-signaling) test signaling server

Create a e2e testcase to test the signaling server.

src/frontend/apps/e2e/__tests__/app-impress/pad-editor.spec.ts

@@ -17,4 +17,30 @@ test.describe('Pad Editor', () => {
     await page.locator('.ProseMirror.bn-editor').fill('Hello World');
     await expect(page.getByText('Hello World')).toBeVisible();
   });
+
+  test('checks the Pad is connected to the webrtc server', async ({ page }) => {
+    const webSocketPromise = page.waitForEvent('websocket', (webSocket) => {
+      return webSocket.url().includes('ws://localhost:4444/');
+    });
+
+    await page.getByText('My mocked pad').first().click();
+    await expect(page.locator('h2').getByText('My mocked pad')).toBeVisible();
+
+    const webSocket = await webSocketPromise;
+    expect(webSocket.url()).toBe('ws://localhost:4444/');
+
+    const framesentPromise = webSocket.waitForEvent('framesent');
+
+    await page.locator('.ProseMirror.bn-editor').click();
+    await page.locator('.ProseMirror.bn-editor').fill('Hello World');
+
+    const framesent = await framesentPromise;
+    const payload = JSON.parse(framesent.payload as string) as {
+      type: string;
+      data: { type: string };
+    };
+
+    expect(payload.type).toBe('publish');
+    expect(payload.data.type).toBe('signal');
+  });
 });