public void Only_registered_users_can_login()
{
var result = _userRegistrationService.ValidateUserAsync("*****@*****.**", "password").Result;
result.ShouldEqual(UserLoginResults.Successful);
result = _userRegistrationService.ValidateUserAsync("*****@*****.**", "password").Result;
result.ShouldEqual(UserLoginResults.NotRegistered);
}