如何使用 Jest 模拟和监视 NestJS 提供者中的“mongoose.connect" [英] How to use Jest to mock and spy a `mongoose.connect` in a provider of NestJS

问题描述

我定义了一个自定义的特定于数据库的Module 以通过 Mongoose API 连接 MongoDB.

I defined a custom database-specific Module to connect a MongoDB via Mongoose APIs.

完整代码在这里.

  {
    provide: DATABASE_CONNECTION,
    useFactory: (dbConfig: ConfigType<typeof mongodbConfig>): Connection =>
      createConnection(dbConfig.uri, {
        useNewUrlParser: true,
        useUnifiedTopology: true,
        //see: https://mongoosejs.com/docs/deprecations.html#findandmodify
        useFindAndModify: false
      }),
    inject: [mongodbConfig.KEY],
  },

在为此提供程序编写测试时，我想确认已定义数据库连接并监视 connect 方法以验证调用的参数.

When writing tests for this provider, I want to confirm the database connection is defined and spy on connect method to verify the called parameters.

我真的需要手动模拟功能，但是有一个一个突然关闭的问题.

I really need the manual mock features, but there is an issue which is closed suddenly.

更新:我尝试使用 ts-jest 中的 mocked，但它不起作用.

UPDATE: I tried to use mocked from ts-jest, but it does not work.

describe('DatabaseProviders(Connectoin)', () => {
  let conn: any;

  jest.mock('mongoose', () => {
    return { createConnection: jest.fn() };
  })

  beforeEach(() => {
    // provide a mock implementation for the mocked createConnection:
    mocked(createConnection).mockImplementation((uri: any, options: any) => {
      return {} as any
    });
  });

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

    conn = module.get<Connection>(DATABASE_CONNECTION);
  });

  afterEach(() => {
    mocked(createConnection).mockClear();
  });

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

  it('connect is called', () => {
    expect(conn).toBeDefined();
    expect(mocked(createConnection).mock.calls.length).toBe(1)
  })

});

运行应用程序时，它抱怨:

When running the application, it complains:

TypeError: utils_1.mocked(...).mockImplementation is not a function

推荐答案

在研究了一些资源并阅读了 Jest 文档后，我自己解决了这个问题.

After researching some resources and read the Jest docs, I resolved this issue myself.

jest.mock('mongoose', () => ({
    createConnection: jest.fn().mockImplementation(
      (uri:any, options:any)=>({} as any)
      ),
    Connection: jest.fn()
  }))

import { ConfigModule } from '@nestjs/config';
import { Test, TestingModule } from '@nestjs/testing';
import { Connection, createConnection } from 'mongoose';
import mongodbConfig from '../config/mongodb.config';
import { databaseConnectionProviders } from './database-connection.providers';
import { DATABASE_CONNECTION } from './database.constants';

describe('DatabaseConnectionProviders', () => {
  let conn: any;

  beforeEach(async () => {
    const module: TestingModule = await Test.createTestingModule({
      imports: [ConfigModule.forFeature(mongodbConfig)],
      providers: [...databaseConnectionProviders],
    }).compile();

    conn = module.get<Connection>(DATABASE_CONNECTION);
  });



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

  it('connect is called', () => {
    //expect(conn).toBeDefined();
    //expect(createConnection).toHaveBeenCalledTimes(1); // it is 2 here. why?
    expect(createConnection).toHaveBeenCalledWith("mongodb://localhost/blog", {
      useNewUrlParser: true,
      useUnifiedTopology: true,
      //see: https://mongoosejs.com/docs/deprecations.html#findandmodify
      useFindAndModify: false
    });
  })

});

在此处查看完整代码.

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