feat: dispatch wheel event (#15593)

packages/playwright-core/src/server/injected/injectedScript.ts

@@ -853,6 +853,7 @@ export class InjectedScript {
       case 'pointer': event = new PointerEvent(type, eventInit); break;
       case 'focus': event = new FocusEvent(type, eventInit); break;
       case 'drag': event = new DragEvent(type, eventInit); break;
+      case 'wheel': event = new WheelEvent(type, eventInit); break;
       default: event = new Event(type, eventInit); break;
     }
     node.dispatchEvent(event);
@@ -1155,7 +1156,7 @@ function oneLine(s: string): string {
   return s.replace(/\n/g, '↵').replace(/\t/g, '⇆');
 }
 
-const eventType = new Map<string, 'mouse' | 'keyboard' | 'touch' | 'pointer' | 'focus' | 'drag'>([
+const eventType = new Map<string, 'mouse' | 'keyboard' | 'touch' | 'pointer' | 'focus' | 'drag' | 'wheel'>([
   ['auxclick', 'mouse'],
   ['click', 'mouse'],
   ['dblclick', 'mouse'],
@@ -1201,6 +1202,8 @@ const eventType = new Map<string, 'mouse' | 'keyboard' | 'touch' | 'pointer' | '
   ['dragleave', 'drag'],
   ['dragexit', 'drag'],
   ['drop', 'drag'],
+
+  ['wheel', 'wheel'],
 ]);
 
 const kHoverHitTargetInterceptorEvents = new Set(['mousemove']);

tests/page/page-dispatchevent.spec.ts

@@ -154,3 +154,20 @@ it('should dispatch click event via ElementHandles', async ({ page, server }) =>
   await button.dispatchEvent('click');
   expect(await page.evaluate(() => window['result'])).toBe('Clicked');
 });
+
+it('should dispatch wheel event', async ({ page, server }) => {
+  it.info().annotations.push({ type: 'issue', description: 'https://github.com/microsoft/playwright/issues/15562' });
+  await page.goto(server.PREFIX + '/input/scrollable.html');
+  const eventsHandle = await page.locator('body').evaluateHandle(e => {
+    const events = [];
+    e.addEventListener('wheel', event => {
+      events.push(event);
+      console.log(event);
+    });
+    return events;
+  });
+  await page.locator('body').dispatchEvent('wheel', { deltaX: 100, deltaY: 200 });
+  expect(await eventsHandle.evaluate(e => e.length)).toBe(1);
+  expect(await eventsHandle.evaluate(e => e[0] instanceof WheelEvent)).toBeTruthy();
+  expect(await eventsHandle.evaluate(e => ({ deltaX: e[0].deltaX, deltaY: e[0].deltaY }))).toEqual({ deltaX: 100, deltaY: 200 });
+});