用于http post catchError的jest的angular 8单元测试

npm install --save-dev jest @types/jest jest-preset-angular

"jest": {
  "preset": "jest-preset-angular",
  "setupFilesAfterEnv": [
    "<rootDir>/src/setup-jest.ts"
  ],
  "testPathIgnorePatterns": [
    "<rootDir>/node_modules/",
    "<rootDir>/dist/"
  ]
}

import 'jest-preset-angular';
import { TestBed } from '@angular/core/testing';
import { HttpClientTestingModule } from '@angular/common/http/testing';

TestBed.configureTestingModule({
  imports: [HttpClientTestingModule]
});

import { TestBed, inject } from '@angular/core/testing';
import { HttpClientTestingModule, HttpTestingController } from '@angular/common/http/testing';
import { MyService } from './my.service';

describe('MyService', () => {
  let service: MyService;
  let httpMock: HttpTestingController;

  beforeEach(() => {
    TestBed.configureTestingModule({
      imports: [HttpClientTestingModule],
      providers: [MyService]
    });

    service = TestBed.inject(MyService);
    httpMock = TestBed.inject(HttpTestingController);
  });

  afterEach(() => {
    httpMock.verify();
  });

  it('should catch error for HTTP POST request', () => {
    const mockError = { message: 'Error occurred' };

    service.postData().subscribe(
      () => fail('Should have failed with an error'),
      error => {
        expect(error).toEqual(mockError);
      }
    );

    const req = httpMock.expectOne('/api/post');
    expect(req.request.method).toBe('POST');

    req.flush(null, { status: 500, statusText: 'Internal Server Error', error: mockError });
  });
});