Jest 单元测试覆盖率

Question

我是 Jest 的新手，希望有人能帮助我。

我目前已将 Jest 集成到我的 Angular 应用程序中，并正在努力提高我的单元测试覆盖率。

我发现我发现了线条。我一直在尝试编写一个测试来覆盖第 16 行 - this.hidePlaceHolder()，但它一直显示为未覆盖。

 @HostListener('ngModelChange') hidePlaceHolderOnChange() {
    this.hidePlaceHolder();
  }

describe('HidePlaceholderDirective', () => {
    // const ren: Renderer2;
    // const elem: ElementRef;
    let directive;
    let directiveEl;
    let fixture: ComponentFixture<DirectiveTestComponent>;
    let component;
    beforeEach(() => {
        TestBed.configureTestingModule({
          declarations: [HidePlaceholderDirective, DirectiveTestComponent],
        }).compileComponents();
        fixture = TestBed.createComponent(DirectiveTestComponent);
        component = fixture.componentInstance;
        directiveEl = fixture.debugElement.query(By.directive(HidePlaceholderDirective));
        directive = directiveEl.injector.get(HidePlaceholderDirective);
      });
 
    it('should create an instance', () => {
        expect(directive).toBeTruthy();
    });
    it('should call hidePlaceholder', () => {
    directiveEl.dispatchEvent(new Event('input'));
    expect(directive.hidePlaceHolder).toHaveBeenCalled();
  });
});