Xunit-und Mock-Daten mit Moq

Ich bin neu in unit-Tests, kann mir jemand beraten, wie Sie testen die öffentliche Methode (CreateUser -) unten mit xUnit und Moq, danke!

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 folgenden Methoden
Überprüfen Sie, ob Benutzer vorhanden ist gibt einfach die Anzahl der bestehenden Benutzer

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);
}

Salz 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();
}

Dank,
J

EDIT 1

Dies ist, was ich habe, so weit:

    [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


        }

Hauptproblem ist, dass ich keine Ahnung habe, wie Mock, set-up Verhalten der privaten Methode "CheckUserExists", wie ihn die Berufung IRepository, welches verspottet wird für die Klasse, so wird diese in diesem Fall die Rücksendung meiner mock-setup für GetAllAsync von dieser privaten Methode ist?

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);

}