public async Task ProcessPaymentAsync_ForValidRequestHavingAmountGreaterThan20AndLessThan500_ExpensiveGatewayIsCalledAndReturnsProcessedStatusAsync()
{
//Arrange
var model = GetPaymentRequestModel(25);
_expensivePaymentGateway.IsAvailableAsync()
.Returns(Task.FromResult(true));
_expensivePaymentGateway.ProcessPaymentAsync(Arg.Any <PaymentRequestModel>())
.Returns(Task.FromResult(PaymentStatus.Processed));
_unitOfWork.PaymentsRepository.When(x => x.AddAsync(Arg.Any <PaymentEntities.Entities.Payment>())).Do(x => { });
_unitOfWork.PaymentsRepository.When(x => x.AddAsync(Arg.Any <PaymentEntities.Entities.Payment>())).Do(x => { });
_unitOfWork.When(x => x.Complete()).Do(x => { });
//Act
var actual = await _paymentBusiness.ProcessPaymentAsync(model);
//Assert
Assert.AreEqual(PaymentStatus.Processed, actual);
_serviceAccessor.Received(1).Invoke(Arg.Any <string>());
await _cheapPaymentGateway.Received(0).ProcessPaymentAsync(Arg.Any <PaymentRequestModel>());
await _expensivePaymentGateway.Received(1).IsAvailableAsync();
await _expensivePaymentGateway.Received(1).ProcessPaymentAsync(Arg.Any <PaymentRequestModel>());
await _unitOfWork.PaymentsRepository.Received(1).AddAsync(Arg.Any <PaymentEntities.Entities.Payment>());
_unitOfWork.Received(1).Complete();
}