public ValidStatusChanges()
            {
                var date   = new DateTime(2020, 3, 1);
                var amount = 10;

                paymentRequest = PaymentRequest.NewPendingPaymentRequest(date, amount);
            }
        public void PaymentRequest_NewPendingPaymentRequest()
        {
            var date   = new DateTime(2020, 3, 1);
            var amount = 10;

            var model = PaymentRequest.NewPendingPaymentRequest(date, amount);

            Assert.Equal(date, model.Date);
            Assert.Equal(amount, model.Amount);
            Assert.Equal(PaymentStatus.Pending, model.Status);
            Assert.True(string.IsNullOrEmpty(model.Reason));
        }