public async Task ChangeUserGenderWithNullUser_ShouldReturnStatusInvalidUser() { var options = new DbContextOptionsBuilder <ApplicationDbContext>() .UseInMemoryDatabase(databaseName: Guid.NewGuid().ToString()).Options; var repository = new EfDeletableEntityRepository <ApplicationUser>(new ApplicationDbContext(options)); var service = new ModelService.ModelService(repository, null, null, null); var user1 = await this.CreateUserAsync("*****@*****.**", "Pesho", "Peshev", repository); var user2 = await this.CreateUserAsync("*****@*****.**", "Vank", "Vanko", repository); var getUser = await repository.All().Where(x => x.Id == user1).FirstOrDefaultAsync(); var changeTo = Gender.Female; var statusInvalid = "Invalid user"; var changeUserGender = await service.ChangeUserGender(null, changeTo); var userCurrentGenderSecondCheck = getUser.ModelInformation.Gender; Assert.Equal(statusInvalid, changeUserGender); Assert.Equal(Gender.Male, userCurrentGenderSecondCheck); }