public void SetUp()
{
SafeProviderForNonExistingUser = CreateSafeProviderForNonExistingUser();
SignUpViewModel = new SignUpViewModel(SafeProviderForNonExistingUser, (safe, userName) => { });
CommandObserver = SignUpViewModel.SignUpCommand.GetDelegateCommandObserver();
ErrorMessagePropertyObserver =
SignUpViewModel.GetPropertyObserver <string>(nameof(SignUpViewModel.SignUpErrorMessage));
}
