public async Task Invoice_Must_Have_Saman_MobileGateway_Enabled()
{
_invoiceBuilder.EnableSamanMobileGateway();
var invoice = await _invoiceBuilder.BuildAsync();
Assert.IsNotNull(invoice);
Assert.IsNotNull(invoice.Properties);
Assert.IsTrue(invoice.Properties.ContainsKey(SamanHelper.MobileGatewayKey));
Assert.IsInstanceOf <bool>(invoice.Properties[SamanHelper.MobileGatewayKey]);
Assert.AreEqual(true, invoice.Properties[SamanHelper.MobileGatewayKey]);
}