Testing Repository in services

March 4, 2022

I am trying to test my Nest application using jest. I am doing a very basic check of my service. like this:

import { Test, TestingModule } from "@nestjs/testing";
import { getRepositoryToken } from "@nestjs/typeorm";
import { Repository } from "typeorm";
import { AuditLog } from "./audit-log.entity";
import { AuditLogService } from "./audit-log.service"


/* const mockAuditLogRepository = () => ({
    find: jest.fn(),
    create: jest.fn(),
    save: jest.fn()
}) */

describe('AuditLogService', () => {
    let service: AuditLogService;
    let repo: Repository<AuditLog>;

    beforeEach(async () => {
        const module: TestingModule = await Test.createTestingModule({
            providers: [
                AuditLogService,
                {
                    provide: getRepositoryToken(AuditLog),
                    useValue: {
                        create: jest.fn()
                    }
                }
            ],
        }).compile();

        service = module.get<AuditLogService>(AuditLogService)
        repo = module.get<Repository<AuditLog>>(getRepositoryToken(AuditLog))
    });

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

I am just trying to check if the service is defined but it is giving me the following error :
“ Nest can’t resolve dependencies of the AuditLogService (?). Please make sure that the argument AuditLogRepository at index [0] is available in the RootTestModule context.

Potential solutions:
- If AuditLogRepository is a provider, is it part of the current RootTestModule?
- If AuditLogRepository is exported from a separate @Module, is that module imported within RootTestModule?
  @Module({
    imports: [ /* the Module containing AuditLogRepository */ ]
  })

What am i doing wrong?

>Solution :

The Problem is you are not injecting the repository in your testing Module and must be doing in the service as you said you have a repository class too.
Hence you need to inject that repository too here along with the service.
This may help.

import { Test, TestingModule } from "@nestjs/testing";
import { AuditLogRepository } from "./audit-log.repository";
import { AuditLogService } from "./audit-log.service"


/* const mockAuditLogRepository = () => ({
    find: jest.fn(),
    create: jest.fn(),
    save: jest.fn()
}) */

describe('AuditLogService', () => {
    let service: AuditLogService;
    let repo: AuditLogRepository;

    beforeEach(async () => {
        const module: TestingModule = await Test.createTestingModule({
            providers: [
                AuditLogService,
                AuditLogRepository,
                {
                    provide: AuditLogRepository,
                    useValue: {
                        create: jest.fn()
                    }
                }
            ],
        }).compile();

        service = module.get<AuditLogService>(AuditLogService)
        repo = module.get<AuditLogRepository>(AuditLogRepository)
    });

    test("it should be defined", () => {
        expect.hasAssertions();
        expect(service).toBeDefined();
        expect(repo).toBeDefined();
    })
})