SpyOn TypeORM 存储库更改单元测试 NestJS 的返回值

Posted 2023-03-10

【中文标题】SpyOn TypeORM 存储库更改单元测试 NestJS 的返回值

【英文标题】：SpyOn TypeORM repository to change the return value for unit testing NestJS

【发布时间】：2019-11-27 16:55:09

【问题描述】：

我想对我的 TypeORM 数据库调用进行单元测试。我已经用有效数据模拟了我所有的 TypeORM 存储库。但我想 SpyOn 存储库并更改 TypeORM 的返回值。我该怎么做？

import INestApplication from '@nestjs/common';
import Test from '@nestjs/testing';
import CommonModule from '@src/common/common.module';
import AuthService from './auth.service';
import Repository from 'typeorm';
import V3User from '@src/database/entity/user.v3entity';
    
describe('AuthService', () => 
    let service: AuthService;
    let app: INestApplication;
        
    beforeEach(async () => 
        const module = await Test.createTestingModule(
            imports: [CommonModule.forRoot(`$process.env.DEV_ENV`)],
            providers: [
                AuthService,     
                provide: 'V3USER_REPOSITORY', useValue: mockRepositoryV3User(),
            ],
        ).compile();
    
        app = module.createNestApplication();
        await app.init();
    
        service = module.get<AuthService>(AuthService);
    );
    

    
    it('test auth service - with non existing user in v3 db', async () => 
                
        jest.spyOn(?????? , 'findOne').mockImplementation(() => undefined);
    
        const res = await service.loginUser("bad token");
    
        await expect(service.tokenBasedAuth('example bad token'))
            .rejects.toThrow('bad token exception');
    );
);

对于正常的测试用例，我像这样模拟数据库：

export const mockRepositoryV3User = () => (
    metadata: 
        columns: [],
        relations: [],
    ,
    findOne: async () =>
        Promise.resolve(
            id: 3,
            email: '[e-mail]',
            first_name: 'david',
            last_name: 'david',
            last_login: '2019-07-15',
            date_joined: '2019-07-15',
        ),
);

【参考方案1】：

好的，在终于开始测试和尝试想法之后，我发现这是一个有效的策略

假设我们已经设置了一个PhotoEntity 具有基本属性，没有什么特别的（id、名称、描述等）

import  Column, Entity, PrimaryGeneratedColumn  from 'typeorm';

@Entity()
export class Photo 
  @PrimaryGeneratedColumn()
  id: number;

  @Column( length: 500 )
  name: string;

  @Column('text')
  description: string;

  @Column()
  filename: string;

  @Column('int')
  views: number;

  @Column()
  isPublished: boolean;

设置PhotoService，如下所示（超级基本，但它会说明这一点）：

import  Injectable  from '@nestjs/common';
import  InjectRepository  from '@nestjs/typeorm';
import  Repository  from 'typeorm';
import  Photo  from './photo.entity';

@Injectable()
export class PhotoService 
  constructor(
    @InjectRepository(Photo)
    private readonly photoRepository: Repository<Photo>,
  ) 

  async findAll(): Promise<Photo[]> 
    return await this.photoRepository.find();
  

我们可以useClass: Repository 这样我们就不必做任何繁重的设置存储库类以用于测试（存储库是从 TypeORM 包中导入的。然后我们可以从模块中获取存储库并将其保存为便于模拟的值，并像这样设置我们的测试：

import  Test, TestingModule  from '@nestjs/testing';
import  PhotoService  from './photo.service';
import  getRepositoryToken  from '@nestjs/typeorm';
import  Photo  from './photo.entity';
import  Repository  from 'typeorm';

describe('PhotoService', () => 
  let service: PhotoService;
  // declaring the repo variable for easy access later
  let repo: Repository<Photo>;

  beforeEach(async () => 
    const module: TestingModule = await Test.createTestingModule(
      providers: [
        PhotoService,
        
          // how you provide the injection token in a test instance
          provide: getRepositoryToken(Photo),
          // as a class value, Repository needs no generics
          useClass: Repository,
        ,
      ],
    ).compile();

    service = module.get<PhotoService>(PhotoService);
    // Save the instance of the repository and set the correct generics
    repo = module.get<Repository<Photo>>(getRepositoryToken(Photo));
  );

  it('should be defined', () => 
    expect(service).toBeDefined();
  );

  it('should return for findAll', async () => 
    // mock file for reuse
    const testPhoto: Photo =  
      id: 'a47ecdc2-77d6-462f-9045-c440c5e4616f',
      name: 'hello',
      description: 'the description',
      isPublished: true,
      filename: 'testFile.png',
      views: 5,
    ;
    // notice we are pulling the repo variable and using jest.spyOn with no issues
    jest.spyOn(repo, 'find').mockResolvedValueOnce([testPhoto]);
    expect(await service.findAll()).toEqual([testPhoto]);
  );
);

针对指定文件或针对所有测试运行测试

▶ npm run test -- photo.service

> nestjs-playground@0.0.1 test ~/Documents/code/nestjs-playground
> jest "photo.service"

 PASS  src/photo/photo.service.spec.ts
  PhotoService
    ✓ should be defined (17ms)
    ✓ should return for findAll (4ms)  < -- test passes with no problem

Test Suites: 1 passed, 1 total
Tests:       2 passed, 2 total
Snapshots:   0 total
Time:        3.372s, estimated 4s
Ran all test suites matching /photo.service/i.

【讨论】：

优秀。完美运行。

如何测试查询是否像 .createQueryBuilder('image').offset(pagination.offset).limit(pagination.limit).getManyAndCount();

对于类似的事情，你需要很多 mockReturnThis() 类型的笑话函数，最后一个是 mockresolvedValue()。你可能最终会得到几个模拟或间谍，每个都被链接减去最后一个，所以一个jest.spyOn(repo, 'createQueryBuilder')，一个jest.spyOn(repo, 'offset'), etc, and your repo should probably set up an initial createQueryBuilder` 方法。为了更深入，这个问题真的应该作为一个单独的问题提出

@asus 正如 Discord 上所讨论的，您试图在同步函数上使用 mockResolvedValueOnce。相反，您应该使用mockReturnValueOnce。

@JayMcDoniel 出于某种原因我收到此错误Error: Cannot spy the find property because it is not a function; undefined given instead 我确定我按照您的步骤操作