How to mock dataSource

[MBach]

Hello,

In your documentation, you're assuming that we can access the datasource directly. However, I have a big service like:

@Injectable()
export class ChuteService extends BaseService {
    constructor(
        private dataSource: DataSource,
        
        @InjectRepository(SomeRepo)
        private someRepo: Repository<SomeRepo>,
        
    ) {
        super()
    }
}

Inside, for some methods I'm using transactions like:

public async updateSomeAttribute(
        attrId : string
    ): Promise<SomeOtherEntity> {
        const queryRunner = this.dataSource.createQueryRunner()
        await queryRunner.connect()
        await queryRunner.startTransaction()
        try {
            let obj: SomeOtherEntity= await queryRunner.manager
                .createQueryBuilder(SomeOtherEntity, "s")
                .innerJoinAndSelect("s.anotherOne", "i")
                .where("s.id = :attrId", { attrId })
                .getOneOrFail()

          
            ent = await queryRunner.manager.save<SomeOtherEntity>(entity)
            await queryRunner.commitTransaction()
            return ent 
        } catch (error) {
            await queryRunner.rollbackTransaction()
            throw new BadRequestException(error, "Transaction failed")
        } finally {
            await queryRunner.release()
        }
    }

How can I use your package in my test? I'd like to reflect that some methods are called in my unit test, and to be able to use the dataSource from my service, but it's injected in my real service

describe("Update some attr", () => {
        it("should update some attr and return a Entity or null", async () => {
            
            const typeorm = new MockTypeORM()
            typeorm.onMock(SomeEntity).toReturn(entity, "getOneOrFail")

            const queryRunner = dataSource.createQueryRunner()
            queryRunner.manager.createQueryBuilder()

            // Call the Service
            const result = await myService.updateSomeAttribute(attrId)

            expect(queryRunner.connect).toHaveBeenCalled()
            expect(queryRunner.startTransaction).toHaveBeenCalled()
            expect(queryRunner.commitTransaction).toHaveBeenCalled()
            expect(queryRunner.release).toHaveBeenCalled()
        })
    })

[jazimabbas]

I haven't tested on Nestjs, but I'll take a look into your example this weekend and then will let you know. Sorry I am overloaded with projects right now. But I'll definitely take a look this weekend.

[Monstermash28425R1]

hello there @MBach, i've been migrating my nestjs services from repositories to dataSource usage, and this is the way i test them:

import { NotFoundException } from '@nestjs/common';
import { Test, TestingModule } from '@nestjs/testing';
import { MockTypeORM } from 'mock-typeorm';
import { send } from 'process';
import { DataSource } from 'typeorm';

import { dataSource } from '../../../../test/mocks/data-source';
import { PaginationMetadata } from '../../../common/dto/pagination-metadata.dto';
import { ApplicationGuard } from '../../../common/guards/application.guard';
import { AuthService } from '../../../modules/auth/services/auth.service';
import { DeviceEntity } from '../../../modules/device/device.entity';
import { DeviceGateway } from '../../../modules/device/device.gateway';
import { CreateDeviceDto } from '../../../modules/device/dto';
import { DeviceService } from '../../../modules/device/services/device.service';
import { ApiConfigService } from '../../../shared/services/api-config.service';
import { DevicesController } from './devices.controller';

describe('DevicesController', () => {
  let controller: DevicesController;
  let typeorm: MockTypeORM;
  beforeEach(async () => {
    typeorm = new MockTypeORM();
    const module: TestingModule = await Test.createTestingModule({
      controllers: [DevicesController],
      providers: [
        DeviceService,
        {
          provide: 'default_IORedisModuleConnectionToken',
          useValue: {},
        },
        {
          provide: DataSource,
          useValue: dataSource,
        },
        {
          provide: ApiConfigService,
          useValue: {
            authConfig: {
              privateKey: 'rsa-private-key',
            },
          },
        },
        {
          provide: AuthService,
          useValue: {
            createAccessToken: () => 'generated-token',
          },
        },
        {
          provide: DeviceGateway,
          useValue: {
            sendCommandTo: () => {},
          },
        },
      ],
    })
      .overrideGuard(ApplicationGuard)
      .useValue({
        canActivate() {
          return true;
        },
      })
      .compile();

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

  afterEach(() => {
    typeorm.restore();
  });

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

and this is my dataSource for mocking:

import { config } from 'dotenv';
import { DataSource } from 'typeorm';

import { UserSubscriber } from '../../src/entity-subscribers/user.subscriber';
import { SnakeNamingStrategy } from '../../src/snake-naming.strategy';

config();

export const dataSource = new DataSource({
  type: 'mysql',
  database: 'mock',
  namingStrategy: new SnakeNamingStrategy(),
  subscribers: [UserSubscriber],
  entities: ['src/**/*.entity.{ts,js}'],
  migrations: ['database/mysql/migrations/*.{ts,js}'],
});

note that i'm moking all the 3rd party dependencies and the guards so i just need to focus in my actual code to be tested, i dont know if this is your solution but it's the implementation i found searching around the internet and doing many attempts :)

[Monstermash28425R1]

@MBach i forgot to put an actual example of the test so here it is:

 describe('findOne', () => {
    it('Must find a building with given ID', async () => {
      const building = [{ id: '1', name: 'Building 1' }];
      typeorm.onMock(BuildingEntity).toReturn(building, 'findOne');

      const result = await service.findOne('1');

      expect(result).toStrictEqual(building);
      expect(
        (dataSource.manager.findOne as SinonSpy)
          .getCall(0)
          .calledWith(BuildingEntity, {
            where: { id: '1' },
            relations: ['organization'],
          }),
      ).toBeTruthy();
    });

    it('Must throw a NotFoundException error if not building is found', async () => {
      typeorm.onMock(BuildingEntity).toReturn(undefined, 'findOne');

      await expect(service.findOne('1')).rejects.toThrow(
        new NotFoundException('Building not found.'),
      );
    });
  });

however, i haven't implement a test for transactions nor query builders yet so i'm not pretty sure what's your issue right now.

[jazimabbas]

@Monstermash28425R1 Thanks for your help. I am also creating another repository to add examples for different frameworks e.g. express, nestjs. I need your help there as well to create examples for nestjs.