Nestjs Testing in signup BadRequestException: email in use error

Question

user.service.ts

async findWithMail(email:string):Promise<any> {
    return this.userRepository.findOne({email});
  }

auth.service.ts

async signup(email:string,password:string,name?:string,surname?:string,phone:string){
    if(email) {
      const users = await this.userService.findWithMail(email);
      if(users) {
        throw new BadRequestException('email in use');
      }
    }
    if(!password) return {error:"password must be!"};
    const salt = randomBytes(8).toString('hex');
    const hash = (await scrypt(password,salt,32)) as Buffer;
    const result = salt + '.' +hash.toString('hex');
    password = result;
    const user = await 
    this.userService.create(email,password,name,surname,phone);
    return user;
}

auth.service.spec.ts

let service:AuthService;
let fakeUsersService: Partial<UserService>;

describe('Auth Service',()=>{

  beforeEach(async() => {
    fakeUsersService = {
      findWithMail:() => Promise.resolve([]),
      create:(email:string,password:string) => Promise.resolve({email,password} as User),
    }
  
    const module = await Test.createTestingModule({
      providers:[AuthService,{
        provide:UserService,
        useValue:fakeUsersService
      }],
    }).compile();
    service = module.get(AuthService);
  });
  
  
  it('can create an instance of auth service',async()=> {
    expect(service).toBeDefined();
  })
  it('throws an error if user signs up with email that is in use', async () => {
      await service.signup('[email protected]', 'asdf')
  });
})

When ı try to run my test its give me error even this email is not in database its give error: BadRequestException: email in use. I couldnt figure out how to solve problem

Answer 1

You can use isExists method instead of findOne.

Also you can add extra check for your findWithMail method. Check the length of db request result. Like if (dbReqResult.length === 0) return false; else true

Answer 2

please put your attention on your mocked user service, especially on findWithEmail function, this part

beforeEach(async() => {
 fakeUsersService = {
  findWithMail:() => Promise.resolve([]),
  create:(email:string,password:string) => 
  Promise.resolve({email,password} as User),
 }
 ...

try to resolve the promise to be null not [] (empty array) or change your if(users) on your auth.service to be if(users.length > 0), why? it because empty array means to be thruthy value so when run through this process on your auth.service

if(email) {
  const users = await this.userService.findWithMail(email);
  // on this part below
  if(users) {
    throw new BadRequestException('email in use');
  }
}

the 'users' executed to be truthy value so it will invoke the error. I hope my explanation will help you, thank you