Nest: Mocking data to test 07-sequelize sample

[markau]

I have a working application based on the 07-sequelize sample, but am confused with the doco that outlines how to mock a model when testing . It talks about a mockModel object but does not provide a more detailed example.

Below is what I have got working. I expect the goal here is to mock the UsersService (repository) - to provide mock data instead of real data - to test controller and service functions without hitting the database.

The below does that, but I have an issue with it - usersController.findOne returns a Promise<User> but when mocked below this type is not constrained. I thought I might instantiate a User model object to provide a mock response (e.g. return new User({ name: "Bob" })), but in doing so I get error Model not initialized: User cannot be instantiated. "User" needs to be added to a Sequelize instance.

This question clearly falls into "support" but I wonder whether we could expand the docs a bit to explain what I am (inevitably) doing wrong here.

import { Test, TestingModule } from '@nestjs/testing';
import { UsersController } from './users.controller';
import { UsersService } from './users.service';
import { getModelToken } from '@nestjs/sequelize';
import { User } from './user.model';

const mockUserService = {
  findOne(id: string) {
    return "some value";
  }
};

describe('Users Controller', () => {
  let usersController: UsersController;

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

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

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

  describe('findOne', () => {
    it('should return User', async () => {
      const result = "some value";
      expect(await usersController.findOne('1')).toBe(result);
    });
  });

});

[kamilmysliwiec]

Please, use our Discord channel (support) for such questions. We are using GitHub to track bugs, feature requests, and potential improvements.

[bodva]

This part of the documentation really needs some improvements.