public void AddNewPayment_ReturnsTrue_GivenCanSaveFile()
{
// Arrange & Act
var mockRepo = new Mock <IPaymentAppDataContext>();
IPaymentRepository paymentRepository = new PaymentRepository(mockRepo.Object);
var newPayment = new Payment();
mockRepo.Setup(repo => repo.WriteFile(newPayment)).Returns(true);
// Act
bool result = paymentRepository.AddNewPayment(newPayment);
// Assert
Assert.True(result);
}