Nest.js单元测试依赖解析失败问题求助

问题一：UsersService测试无法解析UserRepository依赖 #

错误现象 #

运行src/users/users.service.spec.ts时，Nest无法解析UsersService的依赖UserRepository，提示该依赖需在RootTestModule上下文可用，原测试代码仅声明了UsersService作为提供者。

错误日志 #

FAIL  src/users/users.service.spec.ts
  ● UsersService › should be defined

    Nest can't resolve dependencies of the UsersService (?). Please make sure that the argument "UserRepository" at index [0] is available in the RootTestModule context.

    Potential solutions:
    - Is RootTestModule a valid NestJS module?
    - If "UserRepository" is a provider, is it part of the current RootTestModule?
    - If "UserRepository" is exported from a separate @Module, is that module imported within RootTestModule?
      @Module({
        imports: [ /* the Module containing "UserRepository" */ ]
      })

       6 |
       7 |   beforeEach(async () => {
    >  8 |     const module: TestingModule = await Test.createTestingModule({
         |                                   ^
       9 |       providers: [UsersService],
      10 |     }).compile();
      11 |

      at TestingInjector.lookupComponentInParentModules (../node_modules/@nestjs/core/injector/injector.js:254:19)
      at TestingInjector.resolveComponentInstance (../node_modules/@nestjs/core/injector/injector.js:207:33)
      at TestingInjector.resolveComponentInstance (../node_modules/@nestjs/testing/testing-injector.js:19:45)
      at resolveParam (../node_modules/@nestjs/core/injector/injector.js:128:38)
          at async Promise.all (index 0)
      at TestingInjector.resolveConstructorParams (../node_modules/@nestjs/core/injector/injector.js:143:27)
      at TestingInjector.loadInstance (../node_modules/@nestjs/core/injector/injector.js:70:13)
      at TestingInjector.loadProvider (../node_modules/@nestjs/core/injector/injector.js:97:9)
      at ../node_modules/@nestjs/core/injector/instance-loader.js:56:13
          at async Promise.all (index 3)
      at TestingInstanceLoader.createInstancesOfProviders (../node_modules/@nestjs/core/injector/instance-loader.js:55:9)
      at ../node_modules/@nestjs/core/injector/instance-loader.js:40:13
          at async Promise.all (index 1)
      at TestingInstanceLoader.createInstances (../node_modules/@nestjs/core/injector/instance-loader.js:39:9)
      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/core/injector/instance-loader.js:22:13)
      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-instance-loader.js:9:9)
      at TestingModuleBuilder.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-module.builder.js:118:9)
      at TestingModuleBuilder.compile (../node_modules/@nestjs/testing/testing-module.builder.js:74:9)
      at Object.<anonymous> (users/users.service.spec.ts:8:35)

原测试代码 #

import { Test, TestingModule } from '@nestjs/testing';
import { UsersService } from './users.service';

describe('UsersService', () => {
  let service: UsersService;

  beforeEach(async () => {
    const module: TestingModule = await Test.createTestingModule({
      providers: [UsersService],
    }).compile();

    service = module.get<UsersService>(UsersService);
  });

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

修复方案 #

单元测试中需要为UsersService的依赖UserRepository提供模拟实现（或根据实际场景提供真实实例），将模拟的UserRepository添加到测试模块的提供者列表中，确保Nest能解析到该依赖。

修复后的代码 #

import { Test, TestingModule } from '@nestjs/testing';
import { UsersService } from './users.service';
// 根据项目实际路径调整UserRepository的导入路径
import { UserRepository } from './user.repository';

// 模拟UserRepository的核心方法，可根据测试需求扩展
const mockUserRepository = {
  // 示例：模拟findOne方法
  findOne: jest.fn(),
};

describe('UsersService', () => {
  let service: UsersService;

  beforeEach(async () => {
    const module: TestingModule = await Test.createTestingModule({
      providers: [
        UsersService,
        {
          provide: UserRepository,
          useValue: mockUserRepository,
        },
      ],
    }).compile();

    service = module.get<UsersService>(UsersService);
  });

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

问题二：UsersController测试无法解析UsersService和AuthService依赖 #

错误现象 #

运行src/users/users.controller.spec.ts时，Nest无法解析UsersController的依赖UsersService和AuthService，原测试代码仅声明了UsersController作为控制器。

错误日志 #

FAIL  src/users/users.controller.spec.ts
● UsersController › should be defined

Nest can't resolve dependencies of the UsersController (?, AuthService). Please make sure that the argument UsersService at index [0] is available in the RootTestModule context.

Potential solutions:
- Is RootTestModule a valid NestJS module?
- If UsersService is a provider, is it part of the current RootTestModule?
- If UsersService is exported from a separate @Module, is that module imported within RootTestModule?
  @Module({
    imports: [ /* the Module containing UsersService */ ]
  })

   6 |
   7 |   beforeEach(async () => {
>  8 |     const module: TestingModule = await Test.createTestingModule({
     |                                   ^
   9 |       controllers: [UsersController],
  10 |     }).compile();
  11 |

  at TestingInjector.lookupComponentInParentModules (../node_modules/@nestjs/core/injector/injector.js:254:19)
  at TestingInjector.resolveComponentInstance (../node_modules/@nestjs/core/injector/injector.js:207:33)
  at TestingInjector.resolveComponentInstance (../node_modules/@nestjs/testing/testing-injector.js:19:45)
  at resolveParam (../node_modules/@nestjs/core/injector/injector.js:128:38)
      at async Promise.all (index 0)
  at TestingInjector.resolveConstructorParams (../node_modules/@nestjs/core/injector/injector.js:143:27)
  at TestingInjector.loadInstance (../node_modules/@nestjs/core/injector/injector.js:70:13)
  at TestingInjector.loadController (../node_modules/@nestjs/core/injector/injector.js:88:9)
  at ../node_modules/@nestjs/core/injector/instance-loader.js:68:13
      at async Promise.all (index 0)
  at TestingInstanceLoader.createInstancesOfControllers (../node_modules/@nestjs/core/injector/instance-loader.js:67:9)
  at ../node_modules/@nestjs/core/injector/instance-loader.js:42:13
      at async Promise.all (index 1)
  at TestingInstanceLoader.createInstances (../node_modules/@nestjs/core/injector/instance-loader.js:39:9)
  at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/core/injector/instance-loader.js:22:13)
  at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-instance-loader.js:9:9)
  at TestingModuleBuilder.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-module.builder.js:118:9)
  at TestingModuleBuilder.compile (../node_modules/@nestjs/testing/testing-module.builder.js:74:9)
  at Object.<anonymous> (users/users.controller.spec.ts:8:35)

原测试代码（注：原粘贴代码有误，以下为对应UsersController的正确原代码结构） #

import { Test, TestingModule } from '@nestjs/testing';
import { UsersController } from './users.controller';

describe('UsersController', () => {
  let controller: UsersController;

  beforeEach(async () => {
    const module: TestingModule = await Test.createTestingModule({
      controllers: [UsersController],
    }).compile();

    controller = module.get<UsersController>(UsersController);
  });

  it('should be defined', () => {
    expect(controller).toBeDefined();
  });
});

修复方案 #

需要为UsersController的两个依赖UsersService和AuthService提供模拟实现，将这两个模拟提供者添加到测试模块中，确保Nest能解析到所需依赖。

修复后的代码 #

import { Test, TestingModule } from '@nestjs/testing';
import { UsersController } from './users.controller';
import { UsersService } from './users.service';
// 根据项目实际路径调整AuthService的导入路径
import { AuthService } from '../auth/auth.service';

// 模拟UsersService，可根据测试需求扩展方法
const mockUsersService = {
  findUserById: jest.fn(),
};

// 模拟AuthService，可根据测试需求扩展方法
const mockAuthService = {
  validateUser: jest.fn(),
};

describe('UsersController', () => {
  let controller: UsersController;

  beforeEach(async () => {
    const module: TestingModule = await Test.createTestingModule({
      controllers: [UsersController],
      providers: [
        {
          provide: UsersService,
          useValue: mockUsersService,
        },
        {
          provide: AuthService,
          useValue: mockAuthService,
        },
      ],
    }).compile();

    controller = module.get<UsersController>(UsersController);
  });

  it('should be defined', () => {
    expect(controller).toBeDefined();
  });
});

内容的提问来源于stack exchange，提问作者Finddd out