Xunit and Mock data with Moq

Question

I'm new to unit testing, can anyone advise how to test public method (CreateUser) below using xUnit and Moq, thanks!

public async Task<bool> CreateUser(UserDTO newUser)
{
  newUser.CustomerId = _userResolverService.GetCustomerId();
  if (await CheckUserExists(newUser)) return false;
  var salt = GenerateSalt(10);
  var passwordHash = GenerateHash(newUser.Password, salt);

  await _usersRepository.AddAsync(new User()
  {
    Role = newUser.Role,
    CretedOn = DateTime.Now,
    CustomerId = newUser.CustomerId,
    Email = newUser.Email,
    FirstName = newUser.FirstName,
    LastName = newUser.LastName,
    PasswordHash = passwordHash,
    Salt = salt,
    UpdatedOn = DateTime.Now
  });

  return true;
}

Private methods below Check if user exists simply returns number of existing users

private async Task<bool> CheckUserExists(UserDTO user)
    {
      var users = await _usersRepository.GetAllAsync();
      var userCount = users.Count(u => u.Email == user.Email);
      return userCount > 0;
    }

Hash Generation

private static string GenerateHash(string input, string salt)
{
  var bytes = System.Text.Encoding.UTF8.GetBytes(input + salt);
  var sha256 = SHA256.Create();
  var hash = sha256.ComputeHash(bytes);

  return ByteArrayToString(hash);
}

Salt Generaion

private static string GenerateSalt(int size)
{
  var rng = RandomNumberGenerator.Create();
  var buff = new byte[size];
  rng.GetBytes(buff);
  return Convert.ToBase64String(buff);
}



private static string ByteArrayToString(byte[] ba)
{
  var hex = new StringBuilder(ba.Length * 2);
  foreach (byte b in ba)
    hex.AppendFormat("{0:x2}", b);
  return hex.ToString();
}

Thanks, J

EDIT 1

This is what I have so far:

    [Fact]
        public async void CreateUser_True()
        {
          //arrange
          var dataSource = new Mock<IRepository<User, int>>();
          var userResolverService = new Mock<IUserResolverService>();
          var tokenService = new Mock<ITokenService>();

      var users = new List<User>();
      users.Add(new User()
      {
        Email = "[email protected]",
        CustomerId = 1
      });
      dataSource.Setup(m => m.GetAllAsync()).ReturnsAsync(users); // Error Here with converting async task to IEnumerable...

          var accountService = new AccountService(dataSource.Object,userResolverService.Object,tokenService.Object);


          //act


          //assert


        }

Main problem is that I have no idea how to Mock, set up behavior of private Method "CheckUserExists", as it's calling IRepository which is mocked for class, so will this in this case return my mock setup for GetAllAsync from this private method?

EDIT 2

public async Task<TEntity> AddAsync(TEntity entity)
{
  if (entity == null)
  {
    throw new ArgumentNullException(nameof(entity));
  }
  _entities.Add(entity);
  await _context.SaveChangesAsync();
  return entity;
}

EDIT 3

[Fact]
public async void CreateUser_True()
{
  //arrange
  var users = new List<User>();
  users.Add(new User()
  {
    Email = "[email protected]",
    CustomerId = 1
  });
  _dataSource.Setup(m => m.GetAllAsync()).ReturnsAsync(users);
  _dataSource.Setup(m => m.AddAsync(It.IsAny<User>())).Returns<User>(Task.FromResult);
  var accountService = new AccountService(_dataSource.Object, _userResolverService.Object, _tokenService.Object);


  //act
  var result = await accountService.CreateUser(new UserDTO()
  {
    Email = "[email protected]"
  });

  var updatedUsersList = await _dataSource.Object.GetAllAsync();
  var usersCount = updatedUsersList.Count();

  //assert
  Assert.True(result);
  Assert.Equal(2, usersCount);

}

Solution

As the method being tested is async you need to setup all async dependencies to allow the method flow to completion. As for the private method, you want to setup the behavior of any dependencies that are used within that method, which in this case is the users repository.

[Fact]
public async Task CreateUser_True() {
    //arrange
    var usersRepository = new Mock<IRepository<User, int>>();
    var userResolverService = new Mock<IUserResolverService>();
    var tokenService = new Mock<ITokenService>();

    var user = new User() {
        Email = "[email protected]",
        CustomerId = 1
    };
    var users = new List<User>() { user };

    usersRepository.Setup(_ => _.GetAllAsync()).ReturnsAsync(users);
    usersRepository.Setup(_ => _.AddAsync(It.IsAny<User>()))
        .Returns<User>(arg => Task.FromResult(arg)) //<-- returning the input value from task.
        .Callback<User>(arg => users.Add(arg)); //<-- use call back to perform function
    userResolverService.Setup(_ => _.GetCustomerId()).Returns(2);
    var accountService = new AccountService(usersRepository.Object, userResolverService.Object, tokenService.Object);

    //act
    var actual = await accountService.CreateUser(new UserDto { 
        Email = "[email protected]",
        Password = "monkey123",
        //...other code removed for brevity
    });

    //assert
    Assert.IsTrue(actual);
    Assert.IsTrue(users.Count == 2);
    Assert.IsTrue(users.Any(u => u.CustomerId == 2);
}

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