Angular2 测试组件是否有合适的选择器 [英] Angular2 test if component has proper selector

问题描述

Angular2 有没有可能通过单元测试来验证组件选择器?

Is there any possibility in Angular2 to verify component selector with unit test?

例如

@Component({
    selector: 'my-component',
    template: '<p>test</p>'
})
export class MyComponent {}

和

....
it(`Component should have selector 'my-component'`, () => {
    expect(component.selector).toBe('my-component');
});

推荐答案

Reflect 元数据被 Angular DI 用来存储和检索装饰器数据.

Reflect metadata is used by Angular DI to store and retrieve decorator data.

可以从类中获取元数据并对其进行断言:

It is possible to get metadata from the class and assert it:

  const [componentDecorator] = Reflect.getOwnMetadata('annotations', MyComponentClass);

  expect(componentDecorator.selector).toBe('my-component');

其中 Reflect.getMetadata('annotations', ...) 返回类注释数组.

Where Reflect.getMetadata('annotations', ...) returns an array of class annotations.

这需要加载 reflect-metadata 或 core-js/es7/reflect polyfills.这个 polyfill 是 Angular 的先决条件.

This requires reflect-metadata or core-js/es7/reflect polyfills to be loaded. This polyfill is Angular prerequisite.

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