Angular 小吃店服務茉莉花測試

Question

我想用茉莉花測試小吃店服務。 更具體地說，我正在測試以下兩種情況：

1. 服務已創建
2. 里面的方法被調用

小吃店服務

import { Injectable, NgZone } from '@angular/core';
import { MatSnackBar } from '@angular/material';

@Injectable({
  providedIn: 'root'
})
export class SnackbarService {

  constructor(
    public snackBar: MatSnackBar,
    private zone: NgZone
  ) { }

  public open(message, action, duration = 1000) {
    this.zone.run(() => {
      this.snackBar.open(message, action, { duration });
    })
  }
}

小吃店.service.spec

import { TestBed } from '@angular/core/testing';
import { SnackbarService } from './snackbar.service';

describe('SnackbarService', () => {
  beforeEach(() => TestBed.configureTestingModule({}));

  it('should be created', () => {
    const service: SnackbarService = TestBed.get(SnackbarService);
    expect(service).toBeTruthy();
  });

  it('should call open()', () => {
    const service: SnackbarService = TestBed.get(SnackbarService);
    const spy = spyOn(service, 'open');
    service.open('Hello', 'X', 1000);
    expect(spy).toHaveBeenCalled();
  })
});

運行測試后，Karma 給了我以下錯誤：

1. SnackbarService > 應該調用 open() NullInjectorError: StaticInjectorError(DynamicTestModule)[MatSnackBar]: StaticInjectorError(Platform: core)[MatSnackBar]: NullInjectorError: No provider for MatSnackBar！
2. SnackbarService > 應該被創建 NullInjectorError: StaticInjectorError(DynamicTestModule)[MatSnackBar]: StaticInjectorError(Platform: core)[MatSnackBar]: NullInjectorError: No provider for MatSnackBar！

關於我應該如何解決這個問題的任何想法？

謝謝！

Answer 1

是的，您必須導入並提供所需的內容。

import { TestBed } from '@angular/core/testing';
import { SnackbarService } from './snackbar.service';
import { MatSnackBarModule } from '@angular/material/snack-bar';

describe('SnackbarService', () => {
  let zone: NgZone;
  let snackBar: MatSnackBar;
  beforeEach(() => TestBed.configureTestingModule({
     imports: [MatSnackBarModule],
     providers: [
       SnackbarService,
       NgZone,
     ],
  }));

  beforeEach(() => {
    // if you're on Angular 9, .get should be .inject
    zone = TestBed.get(NgZone);
    spyOn(zone, 'run').and.callFake((fn: Function) => fn());
    snackBar = TestBed.get(MatSnackBar);
  });

  it('should be created', () => {
    const service: SnackbarService = TestBed.get(SnackbarService);
    expect(service).toBeTruthy();
  });

  // the way you have written this test, it asserts nothing
  it('should call open()', () => {
    const service: SnackbarService = TestBed.get(SnackbarService);
    // const spy = spyOn(service, 'open');
    const spy = spyOn(snackBar, 'open');
    service.open('Hello', 'X', 1000);
    expect(spy).toHaveBeenCalled();
  })
});

我從來沒有對需要NgZone東西進行過單元測試，但是如果你遇到問題，請調查一下（ 為具有 NgZone 依賴項的組件運行 jasmine 測試）。