如何在我的AngularDart 5测试中使用KeyCode触发KeyDown事件？

import 'dart:html';
import 'package:test/test.dart';
import 'package:angular/angular.dart';
import 'package:angular_test/angular_test.dart';

@Component(
  selector: 'test-component',
  template: '',
)
class TestComponent {}

void main() {
  tearDown(disposeAnyRunningTest);

  test('should trigger key down event with KeyCode', () async {
    final testBed = NgTestBed<TestComponent>();
    final testFixture = await testBed.create();
    final element = testFixture.rootElement;

    final event = KeyboardEvent('keydown', keyCode: KeyCode.ENTER);
    element.dispatchEvent(event);

    // Add your assertions here
    // 验证KeyDown事件是否被触发

    await testFixture.dispose();
  });
}