fix: returning 0 for line price if item is not taxable (#476)

* fix: 🐛 returning 0 for line price if item is not taxable

* build: 👷 add changeset

.changeset/thin-owls-beg.md

@@ -0,0 +1,5 @@
+---
+"saleor-app-taxes": patch
+---
+
+Fix returning 0 for line price if Avatax returns isItemTaxable: false. This happens in, f.e., certain states in the US where there is no sales tax. After the fix, the app will fall back to the original line price.

apps/taxes/src/modules/avatax/maps/avatax-calculate-taxes-map.test.ts

@@ -1,111 +1,88 @@
 import { describe, expect, it } from "vitest";
 import {
-  AvataxCalculateTaxesMapPayloadArgs,
-  avataxCalculateTaxesMaps,
+  SHIPPING_ITEM_CODE,
+  mapPayloadLines,
+  mapResponseProductLines,
+  mapResponseShippingLine,
 } from "./avatax-calculate-taxes-map";
-
-// * Mocked payload data, channel config and avatax config
-const MOCKED_CALCULATE_TAXES_ARGS: AvataxCalculateTaxesMapPayloadArgs = {
-  taxBase: {
-    pricesEnteredWithTax: false,
-    currency: "PLN",
-    channel: {
-      slug: "channel-pln",
-    },
-    sourceObject: {
-      __typename: "Order",
-      user: {
-        id: "VXNlcjo5ZjY3ZjY0Zi1iZjY5LTQ5ZjYtYjQ4Zi1iZjY3ZjY0ZjY0ZjY=",
-      },
-    },
-    discounts: [],
-    address: {
-      streetAddress1: "123 Palm Grove Ln",
-      streetAddress2: "",
-      city: "LOS ANGELES",
-      country: {
-        code: "US",
-      },
-      countryArea: "CA",
-      postalCode: "90002",
-    },
-    shippingPrice: {
-      amount: 48.33,
-    },
-    lines: [
-      {
-        quantity: 3,
-        unitPrice: {
-          amount: 84,
-        },
-        totalPrice: {
-          amount: 252,
-        },
-        sourceLine: {
-          __typename: "OrderLine",
-          id: "T3JkZXJMaW5lOmY1NGQ1MWY2LTc1OTctNGY2OC1hNDk0LTFjYjZlYjRmOTlhMQ==",
-          variant: {
-            id: "UHJvZHVjdFZhcmlhbnQ6MzQ2",
-            product: {
-              metafield: null,
-              productType: {
-                metafield: null,
-              },
-            },
-          },
-        },
-      },
-      {
-        quantity: 1,
-        unitPrice: {
-          amount: 5.99,
-        },
-        totalPrice: {
-          amount: 5.99,
-        },
-        sourceLine: {
-          __typename: "OrderLine",
-          id: "T3JkZXJMaW5lOjU1NTFjNTFjLTM5MWQtNGI0Ny04MGU0LWVjY2Q5ZjU4MjQyNQ==",
-          variant: {
-            id: "UHJvZHVjdFZhcmlhbnQ6Mzg1",
-            product: {
-              metafield: null,
-              productType: {
-                metafield: null,
-              },
-            },
-          },
-        },
-      },
-    ],
-  },
-  channel: {
-    providerInstanceId: "b8c29f49-7cae-4762-8458-e9a27eb83081",
-    enabled: false,
-    address: {
-      country: "US",
-      zip: "92093",
-      state: "CA",
-      city: "La Jolla",
-      street: "9500 Gilman Drive",
-    },
-  },
-  config: {
-    companyCode: "DEFAULT",
-    isAutocommit: false,
-    isSandbox: true,
-    name: "Avatax-1",
-    password: "password",
-    username: "username",
-    shippingTaxCode: "FR000000",
-  },
-};
+import { mapPayloadArgsMocks, transactionModelMocks } from "./mocks";
 
 describe("avataxCalculateTaxesMaps", () => {
-  describe.todo("mapResponse", () => {
-    it.todo("calculation of fields");
-    it.todo("formatting the fields");
-    it.todo("rounding of numbers");
+  describe("mapResponseShippingLine", () => {
+    it("when shipping line is not taxable, returns line amount", () => {
+      const nonTaxableShippingLine = mapResponseShippingLine(transactionModelMocks.nonTaxable);
+
+      expect(nonTaxableShippingLine).toEqual({
+        shipping_price_gross_amount: 77.51,
+        shipping_price_net_amount: 77.51,
+        shipping_tax_rate: 0,
+      });
+    });
+
+    it("when shipping line is taxable and tax is included, returns calculated gross & net amounts", () => {
+      const taxableShippingLine = mapResponseShippingLine(
+        transactionModelMocks.taxable.taxIncluded
+      );
+
+      expect(taxableShippingLine).toEqual({
+        shipping_price_gross_amount: 77.51,
+        shipping_price_net_amount: 70.78,
+        shipping_tax_rate: 0,
+      });
+    });
+
+    it("when shipping line is taxable and tax is not included, returns calculated gross & net amounts", () => {
+      const taxableShippingLine = mapResponseShippingLine(
+        transactionModelMocks.taxable.taxNotIncluded
+      );
+
+      expect(taxableShippingLine).toEqual({
+        shipping_price_gross_amount: 84.87,
+        shipping_price_net_amount: 77.51,
+        shipping_tax_rate: 0,
+      });
+    });
+  });
+  describe("mapResponseProductLines", () => {
+    it("when product lines are not taxable, returns line amount", () => {
+      const nonTaxableProductLines = mapResponseProductLines(transactionModelMocks.nonTaxable);
+
+      expect(nonTaxableProductLines).toEqual([
+        {
+          total_gross_amount: 20,
+          total_net_amount: 20,
+          tax_rate: 0,
+        },
+      ]);
+    });
+
+    it("when product lines are taxable and tax is included, returns calculated gross & net amounts", () => {
+      const taxableProductLines = mapResponseProductLines(
+        transactionModelMocks.taxable.taxIncluded
+      );
+
+      expect(taxableProductLines).toEqual([
+        {
+          total_gross_amount: 40,
+          total_net_amount: 36.53,
+          tax_rate: 0,
+        },
+      ]);
+    });
+
+    it("when product lines are taxable and tax is not included, returns calculated gross & net amounts", () => {
+      const taxableProductLines = mapResponseProductLines(
+        transactionModelMocks.taxable.taxNotIncluded
+      );
+
+      expect(taxableProductLines).toEqual([
+        {
+          total_gross_amount: 43.8,
+          total_net_amount: 40,
+          tax_rate: 0,
+        },
+      ]);
+    });
   });
   describe.todo("mapPayload", () => {
     it.todo("calculation of fields");
@@ -113,17 +90,17 @@ describe("avataxCalculateTaxesMaps", () => {
     it.todo("rounding of numbers");
   });
   describe("mapLines", () => {
-    const lines = avataxCalculateTaxesMaps.mapLines(
-      MOCKED_CALCULATE_TAXES_ARGS.taxBase,
-      MOCKED_CALCULATE_TAXES_ARGS.config
+    const lines = mapPayloadLines(
+      mapPayloadArgsMocks.default.taxBase,
+      mapPayloadArgsMocks.default.config
     );
 
     it("includes shipping as a line", () => {
       expect(lines).toContainEqual({
-        itemCode: avataxCalculateTaxesMaps.shippingItemCode,
+        itemCode: SHIPPING_ITEM_CODE,
         quantity: 1,
         amount: 48.33,
-        taxCode: MOCKED_CALCULATE_TAXES_ARGS.config.shippingTaxCode,
+        taxCode: mapPayloadArgsMocks.default.config.shippingTaxCode,
         taxIncluded: false,
       });
     });

apps/taxes/src/modules/avatax/maps/avatax-calculate-taxes-map.ts

@@ -14,9 +14,9 @@ import { avataxAddressFactory } from "./address-factory";
  * * Shipping is a regular line item in Avatax
  * https://developer.avalara.com/avatax/dev-guide/shipping-and-handling/taxability-of-shipping-charges/
  */
-const SHIPPING_ITEM_CODE = "Shipping";
+export const SHIPPING_ITEM_CODE = "Shipping";
 
-function mapLines(taxBase: TaxBaseFragment, config: AvataxConfig): LineItemModel[] {
+export function mapPayloadLines(taxBase: TaxBaseFragment, config: AvataxConfig): LineItemModel[] {
   const productLines = taxBase.lines.map((line) => ({
     amount: line.totalPrice.amount,
     taxIncluded: taxBase.pricesEnteredWithTax,
@@ -62,49 +62,88 @@ const mapPayload = (props: AvataxCalculateTaxesMapPayloadArgs): CreateTransactio
         shipTo: avataxAddressFactory.fromSaleorAddress(taxBase.address!),
       },
       currencyCode: taxBase.currency,
-      lines: mapLines(taxBase, config),
+      lines: mapPayloadLines(taxBase, config),
       date: new Date(),
     },
   };
 };
 
-const mapResponse = (transaction: TransactionModel): CalculateTaxesResponse => {
+export function mapResponseShippingLine(
+  transaction: TransactionModel
+): Pick<
+  CalculateTaxesResponse,
+  "shipping_price_gross_amount" | "shipping_price_net_amount" | "shipping_tax_rate"
+> {
   const shippingLine = transaction.lines?.find((line) => line.itemCode === SHIPPING_ITEM_CODE);
 
-  const productLines = transaction.lines?.filter((line) => line.itemCode !== SHIPPING_ITEM_CODE);
+  if (!shippingLine?.isItemTaxable) {
+    return {
+      shipping_price_gross_amount: shippingLine?.lineAmount ?? 0,
+      shipping_price_net_amount: shippingLine?.lineAmount ?? 0,
+      /*
+       * avatax doesnt return combined tax rate
+       * // todo: calculate percentage tax rate
+       */
+      shipping_tax_rate: 0,
+    };
+  }
+
   const shippingTaxCalculated = shippingLine?.taxCalculated ?? 0;
   const shippingTaxableAmount = shippingLine?.taxableAmount ?? 0;
   const shippingGrossAmount = numbers.roundFloatToTwoDecimals(
     shippingTaxableAmount + shippingTaxCalculated
   );
-  const shippingNetAmount = shippingGrossAmount;
 
   return {
     shipping_price_gross_amount: shippingGrossAmount,
-    shipping_price_net_amount: shippingNetAmount,
-    // todo: add shipping tax rate
+    shipping_price_net_amount: shippingTaxableAmount,
     shipping_tax_rate: 0,
-    lines:
-      productLines?.map((line) => {
-        const lineTaxCalculated = line.taxCalculated ?? 0;
-        const lineTotalNetAmount = line.taxableAmount ?? 0;
-        const lineTotalGrossAmount = numbers.roundFloatToTwoDecimals(
-          lineTotalNetAmount + lineTaxCalculated
-        );
+  };
+}
 
+export function mapResponseProductLines(
+  transaction: TransactionModel
+): CalculateTaxesResponse["lines"] {
+  const productLines = transaction.lines?.filter((line) => line.itemCode !== SHIPPING_ITEM_CODE);
+
+  return (
+    productLines?.map((line) => {
+      if (!line.isItemTaxable) {
         return {
-          total_gross_amount: lineTotalGrossAmount,
-          total_net_amount: lineTotalNetAmount,
-          // todo: add tax rate
+          total_gross_amount: line.lineAmount ?? 0,
+          total_net_amount: line.lineAmount ?? 0,
           tax_rate: 0,
         };
-      }) ?? [],
+      }
+
+      const lineTaxCalculated = line.taxCalculated ?? 0;
+      const lineTotalNetAmount = line.taxableAmount ?? 0;
+      const lineTotalGrossAmount = numbers.roundFloatToTwoDecimals(
+        lineTotalNetAmount + lineTaxCalculated
+      );
+
+      return {
+        total_gross_amount: lineTotalGrossAmount,
+        total_net_amount: lineTotalNetAmount,
+        /*
+         * avatax doesnt return combined tax rate
+         * // todo: calculate percentage tax rate
+         */ tax_rate: 0,
+      };
+    }) ?? []
+  );
+}
+
+const mapResponse = (transaction: TransactionModel): CalculateTaxesResponse => {
+  const shipping = mapResponseShippingLine(transaction);
+
+  return {
+    ...shipping,
+    lines: mapResponseProductLines(transaction),
   };
 };
 
 export const avataxCalculateTaxesMaps = {
   mapPayload,
   mapResponse,
-  mapLines,
-  shippingItemCode: SHIPPING_ITEM_CODE,
 };