Discount on taxes (OriginProtocol#939)

* Modeled an 'Exclude Taxes' checkbox based on 'Exclude Shipping Fees'. Added tooltips for both to explain their functions

* Frontend Changes: Added a button to make the already-existing 'Delete' option on the Edit Discount page visible. Fixed messaging error in tooltips for 'Exclude Shipping Fees' and 'Exclude Taxes' (see OriginProtocol#653). Backend change: the discount 'model' now has a field to recognize 'Exclude Taxes'

* Backend changes. Reference: OriginProtocol#762

* Adjusted logic that calculates the total tax to be paid. Added comments

* Added tests to discount.test.js, commented on the calculateCartTotal module, cleaned up files

* Substituted the use of an external component for one found in the existing codebase.

* file cleanup

Co-authored-by: Rajath <>

backend/README.md

@@ -98,9 +98,9 @@ To run the full test suite:
 
 To run a specific test or group of tests:
 
-    yarn run test -- -g "Discounts"
+    yarn run test -g "Discounts"
 
-To run a single test, you can change it's function definition from it('blah blah...') to it.only('blah blah...') then run `yarn run test`
+To run a single test, you can change its function definition from it('blah blah...') to it.only('blah blah...') then run `yarn run test`
 
 Optionally, if you are going to run tests several times in a row (typically during development), you can speed up the test setup phase by starting the services in a separate terminal and leave them up and running.
 

backend/db/migrations/202102141140-addExcludeTaxes.js

@@ -0,0 +1,12 @@
+'use strict'
+
+module.exports = {
+  up: (queryInterface, Sequelize) => {
+    return queryInterface.addColumn('discounts', 'exclude_taxes', { 
+      type: Sequelize.BOOLEAN
+    })
+  },
+  down: (queryInterface) => {
+    return queryInterface.removeColumn('discounts', 'exclude_taxes')
+  }
+}

backend/models/discount.js

@@ -38,6 +38,9 @@ module.exports = (sequelize, DataTypes) => {
       excludeShipping: {
         type: DataTypes.BOOLEAN
       },
+      excludeTaxes: {
+        type: DataTypes.BOOLEAN
+      },
       startTime: {
         type: DataTypes.DATE
       },

backend/routes/discounts.js

@@ -14,6 +14,7 @@ const safeDiscountProps = [
   'maxUses',
   'onePerCustomer',
   'excludeShipping',
+  'excludeTaxes',
   'startTime',
   'endTime',
   'data',
@@ -33,6 +34,7 @@ module.exports = function (router) {
         'value',
         'discountType',
         'excludeShipping',
+        'excludeTaxes',
         'maxDiscountValue',
         'minCartValue'
       ])

backend/test/discount.test.js

@@ -14,6 +14,7 @@ const {
 const { processor } = require('../queues/makeOfferProcessor')
 const { Discount } = require('../models')
 const { OrderPaymentStatuses, OrderPaymentTypes } = require('../utils/enums')
+const calculateCartTotal = require('@origin/utils/calculateCartTotal')
 
 describe('Discounts', () => {
   let network,
@@ -376,4 +377,149 @@ describe('Discounts', () => {
       expect(order.data).to.eql(data)
     }
   })
+
+  /*    This test is to confirm that cart totals are being calculated as expected when the 'Exclude Shipping' and 'Exclude Taxes' checkboxes
+  are toggled during discount creation. In other words, this is a test for the interface between created discounts and the 
+  'calculateCartTotal' module.
+  It also checks that user actions (of toggling) are being recorded in the discount object.
+
+  An overview of the discount names is below:
+  shipTax00 - Both 'Exclude Shipping' and 'Exclude Taxes' are unchecked
+  shipTax01 - 'Exclude Shipping' is unchecked.'Exclude Taxes' is checked
+  shipTax10 - 'Exclude Shipping' is checked.'Exclude Taxes' is unchecked
+  shipTax11 - Both 'Exclude Shipping' and 'Exclude Taxes' are checked
+*/
+  it('Should calculate cart totals properly', async () => {
+    const carts = []
+
+    const shipTax00 = await Discount.create({
+      shopId: shop.id,
+      status: 'active',
+      code: '100OFF',
+      discountType: 'percentage',
+      value: 100, // 100% off
+      excludeShipping: false,
+      excludeTaxes: false,
+      startTime: Date.now(),
+      endTime: null,
+      minCartValue: 10,
+      maxDiscountValue: 100,
+      data: null
+    })
+
+    const shipTax01 = await Discount.create({
+      shopId: shop.id,
+      status: 'active',
+      code: '100OFF',
+      discountType: 'percentage',
+      value: 100, // 100% off
+      excludeShipping: false,
+      excludeTaxes: true,
+      startTime: Date.now(),
+      endTime: null,
+      minCartValue: 10,
+      maxDiscountValue: 100,
+      data: null
+    })
+
+    const shipTax10 = await Discount.create({
+      shopId: shop.id,
+      status: 'active',
+      code: '100OFF',
+      discountType: 'percentage',
+      value: 100, // 100% off
+      excludeShipping: true,
+      excludeTaxes: false,
+      startTime: Date.now(),
+      endTime: null,
+      minCartValue: 10,
+      maxDiscountValue: 100,
+      data: null
+    })
+
+    const shipTax11 = await Discount.create({
+      shopId: shop.id,
+      status: 'active',
+      code: '100OFF',
+      discountType: 'percentage',
+      value: 100, // 100% off
+      excludeShipping: true,
+      excludeTaxes: true,
+      startTime: Date.now(),
+      endTime: null,
+      minCartValue: 10 /* read $10 */,
+      maxDiscountValue: 100 /* read $100 */,
+      data: null
+    })
+
+    expect(percentageDiscount).to.have.property('excludeShipping')
+    expect(percentageDiscount).to.have.property('excludeTaxes')
+
+    expect(fixedDiscount).to.have.property('excludeShipping')
+    expect(fixedDiscount).to.have.property('excludeTaxes')
+
+    expect(shipTax00).to.have.property('excludeShipping', false)
+    expect(shipTax00).to.have.property('excludeTaxes', false)
+
+    expect(shipTax11).to.have.property('excludeShipping', true)
+    expect(shipTax11).to.have.property('excludeTaxes', true)
+
+    const discountsToTest = [shipTax00, shipTax01, shipTax10, shipTax11]
+    for (const discount of discountsToTest) {
+      const baseCart = {
+        items: [
+          {
+            product: 'iron-mask',
+            quantity: 1,
+            variant: 1234,
+            price: 8400 /*fixed point integer. Read $84.00*/
+          }
+        ],
+        instructions: '',
+        currency: 'USD',
+        taxRate: 1800 /* 18% */,
+        shipping: {
+          id: 'STANDARD',
+          label: 'Flat Rate',
+          amount: 500 /* fixed point integer. Read $5.00 */
+        },
+        discountObj: discount,
+        userInfo: {
+          /*usually populated, but not necessary for testing*/
+        }
+      }
+      const calculations = calculateCartTotal(baseCart)
+      carts.push({
+        ...baseCart,
+        total: calculations.total,
+        subTotal: calculations.subTotal,
+        discount: calculations.discount,
+        totalTaxes: calculations.totalTaxes
+      })
+    }
+
+    //Cart with the discount 'shipTax00'
+    expect(carts[0].subTotal).to.equal(8400)
+    expect(carts[0].totalTaxes).to.equal(1512) //18% of $84 = $15.12
+    expect(carts[0].discount).to.equal(10000) //Lesser of [100% (subtotal + shipping charges + taxes)] and 'maxDiscountValue'
+    expect(carts[0].total).to.equal(412) //(subtotal + shipping charges + taxes) - discount
+
+    //Cart with the discount 'shipTax01'
+    expect(carts[1].subTotal).to.equal(8400)
+    expect(carts[1].totalTaxes).to.equal(1512)
+    expect(carts[1].discount).to.equal(8900)
+    expect(carts[1].total).to.equal(1512)
+
+    //Cart with the discount 'shipTax10'
+    expect(carts[2].subTotal).to.equal(8400)
+    expect(carts[2].totalTaxes).to.equal(1512)
+    expect(carts[2].discount).to.equal(9912)
+    expect(carts[2].total).to.equal(500)
+
+    //Cart with the discount 'shipTax11'
+    expect(carts[3].subTotal).to.equal(8400)
+    expect(carts[3].totalTaxes).to.equal(1512)
+    expect(carts[3].discount).to.equal(8400)
+    expect(carts[3].total).to.equal(2012)
+  })
 })

packages/utils/calculateCartTotal.js

@@ -2,19 +2,21 @@ const get = require('lodash/get')
 
 /**
  * Accepts cart data and does all the subtotal, taxes,
- * disocunt and total calculations
+ * discount and total calculations
  *
  * @param {Object} cart Cart data object
  *
  * @returns {{
- *  total {Number}
- *  subTotal {Number}
- *  shipping {Number}
- *  discount {Number}
- *  donation {Number}
- *  totalTaxes {Number}
+ *  total {Number},
+ *  subTotal {Number},
+ *  shipping {Number},
+ *  discount {Number},
+ *  donation {Number},
+ *  totalTaxes {Number},
  *  taxRate {Number}
  * }}
+ *
+ * NOTE: total, subTotal, shipping, discount, and totalTaxes are fixed point integers. For ex: $13.89 => 1389
  */
 const calculateCartTotal = (cart) => {
   const cartItems = get(cart, 'items', [])
@@ -24,20 +26,29 @@ const calculateCartTotal = (cart) => {
   }, 0)
 
   const shipping = get(cart, 'shipping.amount', 0)
+
+  //The attribute 'taxRate' of the 'cart' object contains the tax rate as a fixed point number with a "scaling factor" of 1/100
+  //In other words, this number will need to be divided by 100 to get the tax rate in percentage.
+  //[Sources: 'dshop/shop/src/pages/admin/settings/checkout/_CountryTaxEntry.js', 'dshop/shop/src/utils/formHelpers.js']
   const taxRate = parseFloat(get(cart, 'taxRate', 0))
+  const totalTaxes = Math.ceil(((taxRate / 100) * subTotal) / 100)
 
   const discountObj = get(cart, 'discountObj', {})
   const {
     minCartValue,
     maxDiscountValue,
     discountType,
-    excludeShipping
+    excludeShipping,
+    excludeTaxes
   } = discountObj
 
   let discount = 0
 
   const preDiscountTotal =
-    get(cart, 'subTotal', 0) + (excludeShipping ? 0 : shipping)
+    subTotal +
+    (excludeShipping ? 0 : shipping) +
+    (excludeTaxes ? 0 : totalTaxes)
+
   if (!minCartValue || preDiscountTotal > minCartValue * 100) {
     // Calculate discounts only if minCartValue constraint is met
 
@@ -68,7 +79,6 @@ const calculateCartTotal = (cart) => {
 
   const donation = get(cart, 'donation', 0)
 
-  const totalTaxes = Math.ceil(taxRate * subTotal)
   const total = Math.max(
     0,
     subTotal + shipping - discount + donation + totalTaxes

shop/package.json

@@ -46,7 +46,7 @@
     "@origin/ipfs": "^0.1.0",
     "@origin/services": "^0.1.0",
     "@origin/utils": "^0.1.0",
-    "@popperjs/core": "^2.6.0",
+    "@popperjs/core": "^2.9.1",
     "@uphold/uphold-sdk-javascript": "^2.4.0",
     "@web3-react/core": "^6.1.1",
     "@web3-react/injected-connector": "^6.0.7",