如何模拟 typeORM 的 getCustomRepository

Question

我想对一个在其构造函数中使用 getCustomRepository 的类进行单元测试，但我只是想不出一种简单的方法来模拟它。这是我的班级代码

import {getCustomRepository} from 'typeorm';

export class Controller {
  private repository: UserRepository;

  constructor() {
    this.repository = getCustomRepository(UserRepository); //I want to mock this.
  }

  async init() {
    return this.repository.findUser(1);
  }
}

这是测试

describe('User Tests', () => {
  it('should return user', async () => {
    //Fake user to be resolved.
    const user = new User();
    user.id = 2;

    //I want to mock  getCustomRepository(UserRepository); here
    //getCustomRepository = jest.fn().mockResolvedValue(UserRepository); HERE HOW???

    //Mocking find user
    UserRepository.prototype.findUser = jest.fn().mockResolvedValue(user);

    const controller = new Controller();
    const result = await controller.init();
    expect(result).toBeDefined();
  });
});

注意：模拟存储库方法效果很好，但我真的想模拟 getCustomRepository，以便它可以减少尝试连接到数据库所浪费的时间。

这就是 typeORM 中 getCustomRepository 的样子

export declare function getCustomRepository<T>(customRepository: ObjectType<T>, connectionName?: string): T;

用户存储库.ts

@EntityRepository(User)
export class UserRepository extends Repository<User> {
  public async findUser(id: number) {
    return 'real user';
  }
}

用户.ts

@Entity('users')
export class User{
  @PrimaryGeneratedColumn()
  id: number;

  @Column({type: 'varchar', length: 100})
  name: string;
}

所以问题是我如何嘲笑它？任何帮助都感激不尽。

Answer 1

您可以使用jest.mock(moduleName,factory,options)来模拟typeorm模块、getCustomRepository函数及其返回值。

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例如

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controller.ts：

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import { getCustomRepository } from \'typeorm\';\nimport { UserRepository } from \'./userRepo\';\n\nexport class Controller {\n  private repository: UserRepository;\n\n  constructor() {\n    this.repository = getCustomRepository(UserRepository);\n  }\n\n  async init() {\n    return this.repository.findUser(1);\n  }\n}\n

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userRepo.ts：

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export class UserRepository {\n  public async findUser(id: number) {\n    return \'real user\';\n  }\n}\n

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controller.test.ts：

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import { Controller } from \'./controller\';\nimport { getCustomRepository } from \'typeorm\';\nimport { mocked } from \'ts-jest/utils\';\nimport { UserRepository } from \'./userRepo\';\n\njest.mock(\'typeorm\', () => ({ getCustomRepository: jest.fn() }));\n\ndescribe(\'61693597\', () => {\n  it(\'should pass\', async () => {\n    const userRepo = { findUser: jest.fn().mockResolvedValueOnce(\'fake user\') };\n    mocked(getCustomRepository).mockReturnValueOnce(userRepo);\n    const controller = new Controller();\n    const actual = await controller.init();\n    expect(actual).toBe(\'fake user\');\n    expect(getCustomRepository).toBeCalledWith(UserRepository);\n    expect(userRepo.findUser).toBeCalledWith(1);\n  });\n});\n

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带有覆盖率报告的单元测试结果：

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 PASS  stackoverflow/61693597/controller.test.ts (13.53s)\n  61693597\n    \xe2\x9c\x93 should pass (9ms)\n\n---------------|---------|----------|---------|---------|-------------------\nFile           | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s \n---------------|---------|----------|---------|---------|-------------------\nAll files      |   92.31 |      100 |      80 |   90.91 |                   \n controller.ts |     100 |      100 |     100 |     100 |                   \n userRepo.ts   |      80 |      100 |      50 |      75 | 3                 \n---------------|---------|----------|---------|---------|-------------------\nTest Suites: 1 passed, 1 total\nTests:       1 passed, 1 total\nSnapshots:   0 total\nTime:        15.596s\n

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源代码：https://github.com/mrdulin/react-apollo-graphql-starter-kit/tree/master/stackoverflow/61693597

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