单元测试用例检查函数是否被调用

Question

我正在尝试编写一个单元测试用例来检查函数是否在 switch case 中被调用 我有以下功能

public onMessageReceived(event) {
    switch (event && event['event']) {
      case 'onOptionSelected':
        this.toggleNext();
        break;

      case 'temp':
        break;
    }
  }

并已尝试编写与以下相同的单元测试用例，但测试用例总是失败“预期 spy toggleNext 已被调用。”任何可能的问题将不胜感激。

 it('should call toggleNext on onOptionSelected event', () => {
    component.onMessageReceived({ event: 'OptionSelected' });
    fixture.detectChanges();
    fixture.whenStable().then(() => {
      expect(spyOn<any>(component, 'toggleNext')).toHaveBeenCalled();
    });
  });

Answer 1

在调用函数之前先声明间谍

 it('should call toggleNext on onOptionSelected event', () => {
    const toggleSpy = spyOn(component, 'toggleNext');
    component.onMessageReceived({ event: 'onOptionSelected' });
    expect(toggleSpy).toHaveBeenCalled()
  });