Angular 2 中的单元测试和依赖注入

typescript
// app.component.ts
import { Component } from '@angular/core';
@Component({
  selector: 'app-root',
  template: '
{{ title }}
',
})
export class AppComponent {
  title = 'Angular 2 Unit Testing';
}

typescript
// app.component.spec.ts
import { TestBed, ComponentFixture } from '@angular/core/testing';
import { AppComponent } from './app.component';
describe('AppComponent', () => {
  let fixture: ComponentFixture;
  let component: AppComponent;
  beforeEach(() => {
    TestBed.configureTestingModule({
      declarations: [AppComponent],
    });
    fixture = TestBed.createComponent(AppComponent);
    component = fixture.componentInstance;
  });
  it('should create the app', () => {
    expect(component).toBeTruthy();
  });
  it(`should have as title 'Angular 2 Unit Testing'`, () => {
    expect(component.title).toEqual('Angular 2 Unit Testing');
  });
  it('should render title in a h1 tag', () => {
    fixture.detectChanges();
    const compiled = fixture.nativeElement;
    expect(compiled.querySelector('h1').textContent).toContain('Angular 2 Unit Testing');
  });
});

typescript
// log.service.ts
import { Injectable } from '@angular/core';
@Injectable({
  providedIn: 'root',
})
export class LogService {
  log(message: string): void {
    console.log(message);
  }
}

typescript
// log.component.ts
import { Component } from '@angular/core';
import { LogService } from './log.service';
@Component({
  selector: 'app-log',
  template: 'Log Message',
})
export class LogComponent {
  constructor(private logService: LogService) {}
  log(): void {
    this.logService.log('Hello, Angular 2!');
  }
}