public async Task testBuildSetTxnFeesRequestWorksForInvalidFees()
 {
     var ex = await Assert.ThrowsExceptionAsync <InvalidStructureException>(() =>
                                                                            Payments.BuildSetTxnFeesRequestAsync(wallet, DID_TRUSTEE, paymentMethod, "[txnType1:1, txnType2:2]")
                                                                            );
 }
 public async Task TestBuildSetTxnFeesRequestWorksForUnknownPaymentMethod()
 {
     var ex = await Assert.ThrowsExceptionAsync <UnknownPaymentMethodException>(() =>
                                                                                Payments.BuildSetTxnFeesRequestAsync(wallet, DID_TRUSTEE, paymentMethod, fees)
                                                                                );
 }