NestJS测试服务时使用Test.createTestingModule依赖注入失败问题

问题描述 #

在为AdjustmentService编写测试套件时，运行测试返回以下错误：

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

应用运行正常，但测试时依赖注入失败。相关代码如下：

服务构造函数 #

export class AdjustmentService {
  constructor(
    private readonly adjustmentsRepository: AdjustmentRepository,
    private readonly _retailAdjustmentService: RetailAdjustmentService,
    private readonly adjustmentFilesService: AdjustmentFileService
  ) {}
//service functions here...
}

测试代码 #

import { AdjustmentFileService } from "@/services/adjustmentFile.service";
import { Test, TestingModule } from "@nestjs/testing";
import { AdjustmentService } from "./adjustment.service";
import { Repository } from "typeorm";
import { AdjustmentEntity } from "@/entities/adjustment.entity";
import { getRepositoryToken } from "@nestjs/typeorm";
import { RetailAdjustmentService } from "@/services/retail/retailAdjustment.service";

describe("Adjustment Service", () => {
  let adjustmentService: AdjustmentService;
  let adjustementRepository: Repository<AdjustmentEntity>;

  beforeEach(async () => {
    const module = await Test.createTestingModule({
      providers: [
        AdjustmentService,
        AdjustmentFileService,
        RetailAdjustmentService,
        {
          provide: getRepositoryToken(AdjustmentEntity),
          useValue: {
            save: jest.fn(),
            createQueryBuilder: jest.fn(),
            delete: jest.fn(),
            where: jest.fn(),
            execute: jest.fn(),
          },
        },
      ],
    }).compile();

    adjustmentService = module.get<AdjustmentService>(AdjustmentService);
    adjustementRepository = module.get<Repository<AdjustmentEntity>>(
      getRepositoryToken(AdjustmentEntity)
    );
  });

  describe("updateAdjustment", () => {
    it("should update the adjustment", async () => {
      const repoSpy = jest
        .spyOn(adjustementRepository, "save")
        .mockResolvedValue({ id: 1 } as AdjustmentEntity);

      const adjToUpdate = new AdjustmentEntity();
      adjToUpdate.id = 1;
      adjToUpdate.pilars = "RT";
      adjToUpdate.amount = 15000;

      expect(
        adjustmentService.updateAdjustment(1, adjToUpdate)
      ).resolves.toEqual({ id: 1 });

      expect(repoSpy).toBeCalledWith(adjToUpdate);
    });
  });

  it("should return a list of adjustments", async () => {});
});

原因分析 #

问题核心是依赖注入的token不匹配：

• AdjustmentService构造函数中注入的是自定义的AdjustmentRepository类
• 测试代码中却提供了AdjustmentEntity对应的默认Repository的token（getRepositoryToken(AdjustmentEntity)）

Nest无法将这两个token关联，因此找不到AdjustmentRepository的实例。

解决方案 #

需要在测试模块中提供AdjustmentRepository对应的mock实现，使用其专属的token：

修改后的测试代码 #

import { AdjustmentFileService } from "@/services/adjustmentFile.service";
import { Test, TestingModule } from "@nestjs/testing";
import { AdjustmentService } from "./adjustment.service";
import { AdjustmentRepository } from "@/repositories/adjustment.repository"; // 导入自定义Repository
import { RetailAdjustmentService } from "@/services/retail/retailAdjustment.service";

describe("Adjustment Service", () => {
  let adjustmentService: AdjustmentService;
  let adjustementRepository: AdjustmentRepository;

  beforeEach(async () => {
    const module = await Test.createTestingModule({
      providers: [
        AdjustmentService,
        AdjustmentFileService,
        RetailAdjustmentService,
        {
          // 使用自定义Repository作为token
          provide: AdjustmentRepository,
          useValue: {
            save: jest.fn(),
            createQueryBuilder: jest.fn(),
            delete: jest.fn(),
            where: jest.fn(),
            execute: jest.fn(),
            // 按需添加AdjustmentRepository中用到的其他方法
          },
        },
      ],
    }).compile();

    adjustmentService = module.get<AdjustmentService>(AdjustmentService);
    adjustementRepository = module.get<AdjustmentRepository>(AdjustmentRepository);
  });

  describe("updateAdjustment", () => {
    it("should update the adjustment", async () => {
      const repoSpy = jest
        .spyOn(adjustementRepository, "save")
        .mockResolvedValue({ id: 1 } as any);

      const adjToUpdate = { id: 1, pilars: "RT", amount: 15000 };

      await expect(adjustmentService.updateAdjustment(1, adjToUpdate)).resolves.toEqual({ id: 1 });
      expect(repoSpy).toBeCalledWith(adjToUpdate);
    });
  });

  it("should return a list of adjustments", async () => {});
});

关键修改点 #

1. 导入自定义AdjustmentRepository：确保测试文件能引用到该类
2. 替换provide的token：把getRepositoryToken(AdjustmentEntity)改为AdjustmentRepository，自定义Repository本身就是可注入的provider
3. 调整类型声明：将Repository<AdjustmentEntity>改为AdjustmentRepository，保持类型一致
4. 完善mock方法：确保mock对象包含AdjustmentRepository中被调用的所有方法

若你的AdjustmentRepository是通过@EntityRepository（TypeORM旧版）或@Repository（Nest+TypeORM新版）装饰的，也可使用getRepositoryToken(AdjustmentRepository)获取token，效果与直接使用类名一致。

内容的提问来源于stack exchange，提问作者Louguiman