[PM-19180] Calculate sales tax correctly for sponsored plans (#5611)

* [PM-19180] Calculate sales tax correctly for sponsored plans

* Cannot divide by zero if total amount excluding tax is zero.

* Unit tests for families & families for enterprise

---------

Co-authored-by: Conner Turnbull <133619638+cturnbull-bitwarden@users.noreply.github.com>

src/Core/Billing/Models/Api/Requests/Organizations/PreviewOrganizationInvoiceRequestModel.cs

@@ -1,5 +1,6 @@
 using System.ComponentModel.DataAnnotations;
 using Bit.Core.Billing.Enums;
+using Bit.Core.Enums;
 
 namespace Bit.Core.Billing.Models.Api.Requests.Organizations;
 
@@ -20,6 +21,8 @@ public class OrganizationPasswordManagerRequestModel
 {
     public PlanType Plan { get; set; }
 
+    public PlanSponsorshipType? SponsoredPlan { get; set; }
+
     [Range(0, int.MaxValue)]
     public int Seats { get; set; }
 

src/Core/Services/Implementations/StripePaymentService.cs

@@ -1265,7 +1265,7 @@ public class StripePaymentService : IPaymentService
         {
             var invoice = await _stripeAdapter.InvoiceCreatePreviewAsync(options);
 
-            var effectiveTaxRate = invoice.Tax != null && invoice.TotalExcludingTax != null
+            var effectiveTaxRate = invoice.Tax != null && invoice.TotalExcludingTax != null && invoice.TotalExcludingTax.Value != 0
                 ? invoice.Tax.Value.ToMajor() / invoice.TotalExcludingTax.Value.ToMajor()
                 : 0M;
 
@@ -1300,6 +1300,7 @@ public class StripePaymentService : IPaymentService
         string gatewaySubscriptionId)
     {
         var plan = await _pricingClient.GetPlanOrThrow(parameters.PasswordManager.Plan);
+        var isSponsored = parameters.PasswordManager.SponsoredPlan.HasValue;
 
         var options = new InvoiceCreatePreviewOptions
         {
@@ -1325,24 +1326,25 @@ public class StripePaymentService : IPaymentService
             },
         };
 
+        if (isSponsored)
+        {
+            var sponsoredPlan = Utilities.StaticStore.GetSponsoredPlan(parameters.PasswordManager.SponsoredPlan.Value);
+            options.SubscriptionDetails.Items.Add(
+                new() { Quantity = 1, Plan = sponsoredPlan.StripePlanId }
+            );
+        }
+        else
+        {
             if (plan.PasswordManager.HasAdditionalSeatsOption)
             {
                 options.SubscriptionDetails.Items.Add(
-                new()
+                    new() { Quantity = parameters.PasswordManager.Seats, Plan = plan.PasswordManager.StripeSeatPlanId }
-                {
-                    Quantity = parameters.PasswordManager.Seats,
-                    Plan = plan.PasswordManager.StripeSeatPlanId
-                }
                 );
             }
             else
             {
                 options.SubscriptionDetails.Items.Add(
-                new()
+                    new() { Quantity = 1, Plan = plan.PasswordManager.StripePlanId }
-                {
-                    Quantity = 1,
-                    Plan = plan.PasswordManager.StripePlanId
-                }
                 );
             }
 
@@ -1366,6 +1368,7 @@ public class StripePaymentService : IPaymentService
                     });
                 }
             }
+        }
 
         if (!string.IsNullOrWhiteSpace(parameters.TaxInformation.TaxId))
         {
@@ -1420,7 +1423,7 @@ public class StripePaymentService : IPaymentService
         {
             var invoice = await _stripeAdapter.InvoiceCreatePreviewAsync(options);
 
-            var effectiveTaxRate = invoice.Tax != null && invoice.TotalExcludingTax != null
+            var effectiveTaxRate = invoice.Tax != null && invoice.TotalExcludingTax != null && invoice.TotalExcludingTax.Value != 0
                 ? invoice.Tax.Value.ToMajor() / invoice.TotalExcludingTax.Value.ToMajor()
                 : 0M;
 

test/Core.Test/Services/StripePaymentServiceTests.cs

@@ -0,0 +1,227 @@
+using Bit.Core.Billing.Enums;
+using Bit.Core.Billing.Models.Api.Requests;
+using Bit.Core.Billing.Models.Api.Requests.Organizations;
+using Bit.Core.Billing.Models.StaticStore.Plans;
+using Bit.Core.Billing.Pricing;
+using Bit.Core.Billing.Services;
+using Bit.Core.Billing.Services.Contracts;
+using Bit.Core.Enums;
+using Bit.Core.Services;
+using Bit.Core.Test.Billing.Stubs;
+using Bit.Test.Common.AutoFixture;
+using Bit.Test.Common.AutoFixture.Attributes;
+using NSubstitute;
+using Stripe;
+using Xunit;
+
+namespace Bit.Core.Test.Services;
+
+[SutProviderCustomize]
+public class StripePaymentServiceTests
+{
+    [Theory]
+    [BitAutoData]
+    public async Task PreviewInvoiceAsync_ForOrganization_CalculatesSalesTaxCorrectlyForFamiliesWithoutAdditionalStorage(
+        SutProvider<StripePaymentService> sutProvider)
+    {
+        sutProvider.GetDependency<IAutomaticTaxFactory>()
+            .CreateAsync(Arg.Is<AutomaticTaxFactoryParameters>(p => p.PlanType == PlanType.FamiliesAnnually))
+            .Returns(new FakeAutomaticTaxStrategy(true));
+
+        var familiesPlan = new FamiliesPlan();
+        sutProvider.GetDependency<IPricingClient>()
+            .GetPlanOrThrow(Arg.Is<PlanType>(p => p == PlanType.FamiliesAnnually))
+            .Returns(familiesPlan);
+
+        var parameters = new PreviewOrganizationInvoiceRequestBody
+        {
+            PasswordManager = new OrganizationPasswordManagerRequestModel
+            {
+                Plan = PlanType.FamiliesAnnually,
+                AdditionalStorage = 0
+            },
+            TaxInformation = new TaxInformationRequestModel
+            {
+                Country = "FR",
+                PostalCode = "12345"
+            }
+        };
+
+        sutProvider.GetDependency<IStripeAdapter>()
+            .InvoiceCreatePreviewAsync(Arg.Is<InvoiceCreatePreviewOptions>(p =>
+                p.Currency == "usd" &&
+                p.SubscriptionDetails.Items.Any(x =>
+                    x.Plan == familiesPlan.PasswordManager.StripePlanId &&
+                    x.Quantity == 1) &&
+                p.SubscriptionDetails.Items.Any(x =>
+                    x.Plan == familiesPlan.PasswordManager.StripeStoragePlanId &&
+                    x.Quantity == 0)))
+            .Returns(new Invoice
+            {
+                TotalExcludingTax = 4000,
+                Tax = 800,
+                Total = 4800
+            });
+
+        var actual = await sutProvider.Sut.PreviewInvoiceAsync(parameters, null, null);
+
+        Assert.Equal(8M, actual.TaxAmount);
+        Assert.Equal(48M, actual.TotalAmount);
+        Assert.Equal(40M, actual.TaxableBaseAmount);
+    }
+
+    [Theory]
+    [BitAutoData]
+    public async Task PreviewInvoiceAsync_ForOrganization_CalculatesSalesTaxCorrectlyForFamiliesWithAdditionalStorage(
+        SutProvider<StripePaymentService> sutProvider)
+    {
+        sutProvider.GetDependency<IAutomaticTaxFactory>()
+            .CreateAsync(Arg.Is<AutomaticTaxFactoryParameters>(p => p.PlanType == PlanType.FamiliesAnnually))
+            .Returns(new FakeAutomaticTaxStrategy(true));
+
+        var familiesPlan = new FamiliesPlan();
+        sutProvider.GetDependency<IPricingClient>()
+            .GetPlanOrThrow(Arg.Is<PlanType>(p => p == PlanType.FamiliesAnnually))
+            .Returns(familiesPlan);
+
+        var parameters = new PreviewOrganizationInvoiceRequestBody
+        {
+            PasswordManager = new OrganizationPasswordManagerRequestModel
+            {
+                Plan = PlanType.FamiliesAnnually,
+                AdditionalStorage = 1
+            },
+            TaxInformation = new TaxInformationRequestModel
+            {
+                Country = "FR",
+                PostalCode = "12345"
+            }
+        };
+
+        sutProvider.GetDependency<IStripeAdapter>()
+            .InvoiceCreatePreviewAsync(Arg.Is<InvoiceCreatePreviewOptions>(p =>
+                p.Currency == "usd" &&
+                p.SubscriptionDetails.Items.Any(x =>
+                    x.Plan == familiesPlan.PasswordManager.StripePlanId &&
+                    x.Quantity == 1) &&
+                p.SubscriptionDetails.Items.Any(x =>
+                    x.Plan == familiesPlan.PasswordManager.StripeStoragePlanId &&
+                    x.Quantity == 1)))
+            .Returns(new Invoice
+            {
+                TotalExcludingTax = 4000,
+                Tax = 800,
+                Total = 4800
+            });
+
+        var actual = await sutProvider.Sut.PreviewInvoiceAsync(parameters, null, null);
+
+        Assert.Equal(8M, actual.TaxAmount);
+        Assert.Equal(48M, actual.TotalAmount);
+        Assert.Equal(40M, actual.TaxableBaseAmount);
+    }
+
+    [Theory]
+    [BitAutoData]
+    public async Task PreviewInvoiceAsync_ForOrganization_CalculatesSalesTaxCorrectlyForFamiliesForEnterpriseWithoutAdditionalStorage(
+        SutProvider<StripePaymentService> sutProvider)
+    {
+        sutProvider.GetDependency<IAutomaticTaxFactory>()
+            .CreateAsync(Arg.Is<AutomaticTaxFactoryParameters>(p => p.PlanType == PlanType.FamiliesAnnually))
+            .Returns(new FakeAutomaticTaxStrategy(true));
+
+        var familiesPlan = new FamiliesPlan();
+        sutProvider.GetDependency<IPricingClient>()
+            .GetPlanOrThrow(Arg.Is<PlanType>(p => p == PlanType.FamiliesAnnually))
+            .Returns(familiesPlan);
+
+        var parameters = new PreviewOrganizationInvoiceRequestBody
+        {
+            PasswordManager = new OrganizationPasswordManagerRequestModel
+            {
+                Plan = PlanType.FamiliesAnnually,
+                SponsoredPlan = PlanSponsorshipType.FamiliesForEnterprise,
+                AdditionalStorage = 0
+            },
+            TaxInformation = new TaxInformationRequestModel
+            {
+                Country = "FR",
+                PostalCode = "12345"
+            }
+        };
+
+        sutProvider.GetDependency<IStripeAdapter>()
+            .InvoiceCreatePreviewAsync(Arg.Is<InvoiceCreatePreviewOptions>(p =>
+                p.Currency == "usd" &&
+                p.SubscriptionDetails.Items.Any(x =>
+                    x.Plan == "2021-family-for-enterprise-annually" &&
+                    x.Quantity == 1) &&
+                p.SubscriptionDetails.Items.Any(x =>
+                    x.Plan == familiesPlan.PasswordManager.StripeStoragePlanId &&
+                    x.Quantity == 0)))
+            .Returns(new Invoice
+            {
+                TotalExcludingTax = 0,
+                Tax = 0,
+                Total = 0
+            });
+
+        var actual = await sutProvider.Sut.PreviewInvoiceAsync(parameters, null, null);
+
+        Assert.Equal(0M, actual.TaxAmount);
+        Assert.Equal(0M, actual.TotalAmount);
+        Assert.Equal(0M, actual.TaxableBaseAmount);
+    }
+
+    [Theory]
+    [BitAutoData]
+    public async Task PreviewInvoiceAsync_ForOrganization_CalculatesSalesTaxCorrectlyForFamiliesForEnterpriseWithAdditionalStorage(
+        SutProvider<StripePaymentService> sutProvider)
+    {
+        sutProvider.GetDependency<IAutomaticTaxFactory>()
+            .CreateAsync(Arg.Is<AutomaticTaxFactoryParameters>(p => p.PlanType == PlanType.FamiliesAnnually))
+            .Returns(new FakeAutomaticTaxStrategy(true));
+
+        var familiesPlan = new FamiliesPlan();
+        sutProvider.GetDependency<IPricingClient>()
+            .GetPlanOrThrow(Arg.Is<PlanType>(p => p == PlanType.FamiliesAnnually))
+            .Returns(familiesPlan);
+
+        var parameters = new PreviewOrganizationInvoiceRequestBody
+        {
+            PasswordManager = new OrganizationPasswordManagerRequestModel
+            {
+                Plan = PlanType.FamiliesAnnually,
+                SponsoredPlan = PlanSponsorshipType.FamiliesForEnterprise,
+                AdditionalStorage = 1
+            },
+            TaxInformation = new TaxInformationRequestModel
+            {
+                Country = "FR",
+                PostalCode = "12345"
+            }
+        };
+
+        sutProvider.GetDependency<IStripeAdapter>()
+            .InvoiceCreatePreviewAsync(Arg.Is<InvoiceCreatePreviewOptions>(p =>
+                p.Currency == "usd" &&
+                p.SubscriptionDetails.Items.Any(x =>
+                    x.Plan == "2021-family-for-enterprise-annually" &&
+                    x.Quantity == 1) &&
+                p.SubscriptionDetails.Items.Any(x =>
+                    x.Plan == familiesPlan.PasswordManager.StripeStoragePlanId &&
+                    x.Quantity == 1)))
+            .Returns(new Invoice
+            {
+                TotalExcludingTax = 400,
+                Tax = 8,
+                Total = 408
+            });
+
+        var actual = await sutProvider.Sut.PreviewInvoiceAsync(parameters, null, null);
+
+        Assert.Equal(0.08M, actual.TaxAmount);
+        Assert.Equal(4.08M, actual.TotalAmount);
+        Assert.Equal(4M, actual.TaxableBaseAmount);
+    }
+}