Nest Js Jest 单元测试：提供 controller 未使用的模拟实现

Question

作为我之前工作的一部分，我已经实现了一个模拟 class，我想将其作为 Jest 单元测试的一部分提供。

让我用代码解释，这样更好：

我的 Controller 代码：

export class VpcController {
  constructor(private readonly vpcService: VpcService) {}
  @Get
    list() {
    return this.vpcService.list();
  }
}

我的 controller Jest 单元测试：

class VpcServiceMockFactory {
  private list() {
    return jest.fn().mockResolvedValue([TEMPLATE_VPC]);
  }

  getMock() {
    const repoService: RepositoryService = new RepositoryService();
    const vpsServiceMock: VpcServiceMock = new VpcServiceMock(repoService);
    vpsServiceMock.create(TEMPLATE_VPC.name);

    // This works
    // return {
    //   list: this.list(),
    // }

    // This does not work
    return {
      list: vpsServiceMock.list(),
      get: vpsServiceMock.get(TEMPLATE_VPC.id),
      // create: vpsServiceMock.create('new-vpc'),
      // update: vpsServiceMock.update(TEMPLATE_VPC.id, 'updated-name'),
      // delete: vpsServiceMock.delete(TEMPLATE_VPC.id),
    }
  }
}
describe('VpcControllerTest', () => {
  let controller: VpcController;
  let spyService: VpcService;

  beforeEach(async () => {
    // Mock Services
    const MockVpcServiceProvider = {
      provide: VpcService,
      useFactory: () => new VpcServiceMockFactory().getMock()
    }

    // Class-unter-test instantiation
    const module: TestingModule = await Test.createTestingModule({
      controllers: [VpcController],
      providers: [VpcService, MockVpcServiceProvider],
    }).compile()

    // Get the instance handlers
    controller = module.get<VpcController>(VpcController);
    spyService = module.get<VpcService>(VpcService);
  });

  it('Get collection of VPCs', async () => {
    // Execute the method
    const result = await controller.list();

    // Assertion
    expect(spyService.list).toHaveBeenCalled();
    expect(result.length).toBe(1);
    expect(result[0].name).toBe('zopa');
  });
}

我的 VpcServiceMock class：

export class VpcServiceMock {
  constructor(private repository: RepositoryService) {}
  list() {
    return this.repository.list<VpcModel>(VPC);
  }
}

我的存储服务 class：

  async list<T>(type: VPC): Promise<T[]> {
    return <T[]>this.aSimpleJsonObject[type];
  }

但是，当我运行它时，它显示此错误：

  ● VpcControllerTest › Test-2: Get collection of VPCs                                                                                                             
                                                                                                                                                                   
    TypeError: this.vpcService.list is not a function

      38 |   @ApiForbiddenResponse({ description: 'Unauthorized Request' })
      39 |   list() {
    > 40 |     return this.vpcService.list();
         |                            ^
      41 |   }
      42 |
      43 |   @Get(':id')

      at VpcController.list (src/vpc/vpc.controller.ts:40:28)
      at Object.<anonymous> (src/vpc/vpc.controller.spec.ts:87:37)

所以我能让它工作的唯一方法是：

如果我在 Jest 单元测试的VpcServiceMockFactory class 中提供模拟实现（就像我在注释掉的代码中显示的// This works ）。

我肯定在这里遗漏了一些我无法弄清楚的东西。

Answer 1

得到我的问题。

基本上我错过了jest.fn().mockResolvedValue 。

修改以使其工作：

class VpcServiceMockFactory {
  async getMock() {
    const repoService: RepositoryService = new RepositoryService();
    const vpcServiceMock: VpcServiceMock = new VpcServiceMock(repoService);
    await vpcServiceMock.create(TEMPLATE_VPC.name);  // repository store initialization

    return {
      list: jest.fn().mockResolvedValue(vpcServiceMock.list()),
      get: jest.fn().mockResolvedValue(vpcServiceMock.get(TEMPLATE_VPC.id)),
      create: jest.fn().mockResolvedValue(vpcServiceMock.create('new-vpc')),
      update: jest.fn().mockResolvedValue(vpcServiceMock.update(TEMPLATE_VPC.id, 'updated-name')),
      delete: jest.fn().mockResolvedValue(vpcServiceMock.delete(TEMPLATE_VPC.id)),
    }
  }
}