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.