angular-docs-cn/packages/core/test/acceptance/component_spec.ts

/**
 * @license
 * Copyright Google Inc. All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */

import {Component, ComponentFactoryResolver, ComponentRef, InjectionToken, NgModule, OnDestroy, Type, ViewChild, ViewContainerRef, ViewEncapsulation} from '@angular/core';
import {TestBed} from '@angular/core/testing';
import {expect} from '@angular/platform-browser/testing/src/matchers';


describe('component', () => {
  describe('view destruction', () => {
    it('should invoke onDestroy only once when a component is registered as a provider', () => {
      const testToken = new InjectionToken<ParentWithOnDestroy>('testToken');
      let destroyCalls = 0;

      @Component({
        selector: 'comp-with-on-destroy',
        template: '',
        providers: [{provide: testToken, useExisting: ParentWithOnDestroy}]
      })
      class ParentWithOnDestroy {
        ngOnDestroy() { destroyCalls++; }
      }

      @Component({selector: 'child', template: ''})
      class ChildComponent {
        // We need to inject the parent so the provider is instantiated.
        constructor(_parent: ParentWithOnDestroy) {}
      }

      @Component({
        template: `
          <comp-with-on-destroy>
            <child></child>
          </comp-with-on-destroy>
        `
      })
      class App {
      }

      TestBed.configureTestingModule({declarations: [App, ParentWithOnDestroy, ChildComponent]});
      const fixture = TestBed.createComponent(App);
      fixture.detectChanges();
      fixture.destroy();

      expect(destroyCalls).toBe(1, 'Expected `ngOnDestroy` to only be called once.');
    });
  });

  it('should support entry components from another module', () => {
    @Component({selector: 'other-component', template: `bar`})
    class OtherComponent {
    }

    @NgModule({
      declarations: [OtherComponent],
      exports: [OtherComponent],
      entryComponents: [OtherComponent]
    })
    class OtherModule {
    }

    @Component({
      selector: 'test_component',
      template: `foo|<ng-template #vc></ng-template>`,
      entryComponents: [OtherComponent]
    })
    class TestComponent {
      @ViewChild('vc', {read: ViewContainerRef}) vcref !: ViewContainerRef;

      constructor(private _cfr: ComponentFactoryResolver) {}

      createComponentView<T>(cmptType: Type<T>): ComponentRef<T> {
        const cf = this._cfr.resolveComponentFactory(cmptType);
        return this.vcref.createComponent(cf);
      }
    }

    TestBed.configureTestingModule({declarations: [TestComponent], imports: [OtherModule]});
    const fixture = TestBed.createComponent(TestComponent);
    fixture.detectChanges();

    fixture.componentInstance.createComponentView(OtherComponent);
    fixture.detectChanges();
    expect(fixture.nativeElement).toHaveText('foo|bar');
  });

  // TODO: add tests with Native once tests run in real browser (domino doesn't support shadow root)
  describe('encapsulation', () => {
    @Component({
      selector: 'wrapper',
      encapsulation: ViewEncapsulation.None,
      template: `<encapsulated></encapsulated>`
    })
    class WrapperComponent {
    }

    @Component({
      selector: 'encapsulated',
      encapsulation: ViewEncapsulation.Emulated,
      // styles array must contain a value (even empty) to trigger `ViewEncapsulation.Emulated`
      styles: [``],
      template: `foo<leaf></leaf>`
    })
    class EncapsulatedComponent {
    }

    @Component(
        {selector: 'leaf', encapsulation: ViewEncapsulation.None, template: `<span>bar</span>`})
    class LeafComponent {
    }

    beforeEach(() => {
      TestBed.configureTestingModule(
          {declarations: [WrapperComponent, EncapsulatedComponent, LeafComponent]});
    });

    it('should encapsulate children, but not host nor grand children', () => {
      const fixture = TestBed.createComponent(WrapperComponent);
      fixture.detectChanges();
      expect(fixture.nativeElement.innerHTML)
          .toMatch(
              /<encapsulated _nghost-[a-z\-]+(\d+)="">foo<leaf _ngcontent-[a-z\-]+\1=""><span>bar<\/span><\/leaf><\/encapsulated>/);
    });

    it('should encapsulate host', () => {
      const fixture = TestBed.createComponent(EncapsulatedComponent);
      fixture.detectChanges();
      const html = fixture.nativeElement.outerHTML;
      const match = html.match(/_nghost-([a-z\-]+\d+)/);
      expect(match).toBeDefined();
      expect(html).toMatch(new RegExp(`<leaf _ngcontent-${match[1]}=""><span>bar</span></leaf>`));
    });

    it('should encapsulate host and children with different attributes', () => {
      // styles array must contain a value (even empty) to trigger `ViewEncapsulation.Emulated`
      TestBed.overrideComponent(
          LeafComponent, {set: {encapsulation: ViewEncapsulation.Emulated, styles: [``]}});
      const fixture = TestBed.createComponent(EncapsulatedComponent);
      fixture.detectChanges();
      const html = fixture.nativeElement.outerHTML;
      const match = html.match(/_nghost-([a-z\-]+\d+)/g);
      expect(match).toBeDefined();
      expect(match.length).toEqual(2);
      expect(html).toMatch(
          `<leaf ${match[0].replace('_nghost', '_ngcontent')}="" ${match[1]}=""><span ${match[1].replace('_nghost', '_ngcontent')}="">bar</span></leaf></div>`);
    });
  });

  describe('view destruction', () => {
    it('should invoke onDestroy when directly destroying a root view', () => {
      let wasOnDestroyCalled = false;

      @Component({selector: 'comp-with-destroy', template: ``})
      class ComponentWithOnDestroy implements OnDestroy {
        ngOnDestroy() { wasOnDestroyCalled = true; }
      }

      // This test asserts that the view tree is set up correctly based on the knowledge that this
      // tree is used during view destruction. If the child view is not correctly attached as a
      // child of the root view, then the onDestroy hook on the child view will never be called
      // when the view tree is torn down following the destruction of that root view.
      @Component({selector: `test-app`, template: `<comp-with-destroy></comp-with-destroy>`})
      class TestApp {
      }

      TestBed.configureTestingModule({declarations: [ComponentWithOnDestroy, TestApp]});
      const fixture = TestBed.createComponent(TestApp);
      fixture.detectChanges();
      fixture.destroy();
      expect(wasOnDestroyCalled)
          .toBe(
              true,
              'Expected component onDestroy method to be called when its parent view is destroyed');
    });
  });
});