NestJS 错误：错误：Nest 无法解析 AuthService (?, JwtService) 的依赖项答案

【问题标题】：NestJS Error: Error: Nest can't resolve dependencies of the AuthService (?, JwtService)NestJS 错误：错误：Nest 无法解析 AuthService (?, JwtService) 的依赖项
【发布时间】：2020-08-12 14:53:58
【问题描述】：

我第一次尝试测试我的 Nest.js 应用程序。但是当我尝试运行它时，几乎所有由 cli 默认创建的测试都失败了......我读到它是数据库连接的问题，所以我尝试使用 mongodb-memory-server，但它仍然不会不工作。这里有谁知道如何解决这个问题？在我创建构建管道时，所有测试都成功非常重要...

auth.service.ts

import { Injectable } from '@nestjs/common';
import { UsersService } from '../users/users.service';
import { JwtService } from '@nestjs/jwt';

@Injectable()
export class AuthService {
  constructor(private readonly usersService: UsersService, private jwtService: JwtService) {}

  async validateLoginUser(username: string, pass: string): Promise<any> {
    const user = await this.usersService.findByUsernameOrEmail(username);
    if (user && await user.comparePassword(pass)) {
      return user;
    }
    return null;
  }
  async validateFacebookUser(profile): Promise<any> {
    return await this.usersService.findByFacebookIdOrEmail(profile.id, profile.emails[0].value);
  }
  async validateJwtUser(payload): Promise<any> {
    return await this.usersService.findByJwtPayload(payload);
  }

  async login(user: any) {
    const payload = { username: user.username, sub: user.id };
    return {
      access_token: this.jwtService.sign(payload),
    };
  }
}

auth.service.spec.ts

import { Test, TestingModule } from '@nestjs/testing';
import { AuthService } from './auth.service';
import { MongooseModule } from '@nestjs/mongoose';
import { MongoMemoryServer } from 'mongodb-memory-server';
import { JwtModule } from '@nestjs/jwt';
import { PassportModule } from '@nestjs/passport';

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

  beforeEach(async () => {
    const module: TestingModule = await Test.createTestingModule({
      providers: [AuthService],
      imports: [
        PassportModule.register({defaultStrategy: 'jwt'}),
        JwtModule.register({secret: 'secret'}),
        MongooseModule.forRootAsync({
          useFactory: async () => {
            const mongod = new MongoMemoryServer();
            const uri = await mongod.getUri();
            return {
              uri,
            };
          },
        },
      )],
    }).compile();

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

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

错误

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

    at Injector.lookupComponentInExports (/home/olivier/Projects/bp/bp-website-back-nest/node_modules/@nestjs/core/injector/injector.js:183:19)
    at Injector.resolveComponentInstance (/home/olivier/Projects/bp/bp-website-back-nest/node_modules/@nestjs/core/injector/injector.js:143:33)
    at resolveParam (/home/olivier/Projects/bp/bp-website-back-nest/node_modules/@nestjs/core/injector/injector.js:96:38)
    at async Promise.all (index 0)
    at Injector.resolveConstructorParams (/home/olivier/Projects/bp/bp-website-back-nest/node_modules/@nestjs/core/injector/injector.js:112:27)
    at Injector.loadInstance (/home/olivier/Projects/bp/bp-website-back-nest/node_modules/@nestjs/core/injector/injector.js:78:9)
    at Injector.loadProvider (/home/olivier/Projects/bp/bp-website-back-nest/node_modules/@nestjs/core/injector/injector.js:35:9)
    at async Promise.all (index 3)
    at InstanceLoader.createInstancesOfProviders (/home/olivier/Projects/bp/bp-website-back-nest/node_modules/@nestjs/core/injector/instance-loader.js:41:9)
    at /home/olivier/Projects/bp/bp-website-back-nest/node_modules/@nestjs/core/injector/instance-loader.js:27:13
    at async Promise.all (index 1)
    at InstanceLoader.createInstances (/home/olivier/Projects/bp/bp-website-back-nest/node_modules/@nestjs/core/injector/instance-loader.js:26:9)
    at InstanceLoader.createInstancesOfDependencies (/home/olivier/Projects/bp/bp-website-back-nest/node_modules/@nestjs/core/injector/instance-loader.js:16:9)
    at TestingModuleBuilder.compile (/home/olivier/Projects/bp/bp-website-back-nest/node_modules/@nestjs/testing/testing-module.builder.js:38:9)

【问题讨论】：

请添加您的AuthService 定义
我添加了 AuthService 定义

标签： mongoose jestjs nestjs

【解决方案1】：

在 Nest.js 中，所有需要的 Provider 在创建 Provider 实例时都应该可用。在这种情况下，您正在创建一个测试模块，但是 UserService:

不会从您importing 的任何模块中导出（很明显，因为它们是第三方模块，而不是域模块）
providers数组中没有定义

所以 Nest.js 告诉你它在任何地方都找不到 Provider。

将它添加到providers，如[AuthService, UserService]（如有必要，还可以添加其他）应该使 Nest.js 能够找到它、加载它，然后为您提供服务。

【讨论】：