PP-11288-Improve Validation on Prefilled Payment Links

- Updated the session data handling logic which determined a prefilled journey and used the paymentLinkSession attribute
- Added test for the amount page for non-prefilled payment link scenario.
- Added test for the confirmation page prefilled payment link scenario.

app/payment-links/amount/amount.controller.js

@@ -73,8 +73,6 @@ function postPage (req, res, next) {
   const paymentAmountInPence = convertPoundsAndPenceToPence(paymentAmount)
 
   paymentLinkSession.setAmount(req, product.externalId, paymentAmountInPence)
-  paymentLinkSession.setPrefilledFlag(req, product.externalId, 'false')
-
   return res.redirect(replaceParamsInPath(paths.paymentLinks.confirm, product.externalId))
 }
 

app/payment-links/amount/amount.controller.test.js

@@ -234,6 +234,32 @@ describe('Amount Page Controller', () => {
       sinon.assert.calledWith(res.locals.__p, 'paymentLinks.fieldValidation.enterAnAmountInPounds')
     })
 
+    it('when a zero value amount is entered, it should display an error message and the back link correctly', () => {
+      req = {
+        correlationId: '123',
+        product,
+        body: {
+          'payment-amount': '0.00'
+        }
+      }
+
+      res = {
+        redirect: sinon.spy(),
+        locals: {
+          __p: sinon.spy()
+        }
+      }
+
+      controller.postPage(req, res)
+
+      sinon.assert.calledWith(responseSpy, req, res, 'amount/amount')
+
+      const pageData = mockResponses.response.args[0][3]
+      expect(pageData.backLinkHref).to.equal('/pay/an-external-id/reference')
+
+      sinon.assert.calledWith(res.locals.__p, 'paymentLinks.fieldValidation.enterANonZeroAmountInPounds')
+    })
+
     it('when an invalid amount is entered and the change query parameter is present, it should display an error' +
       'message and set the back link to the CONFIRM page', () => {
       req = {

app/payment-links/confirm/confirm.controller.js

@@ -10,14 +10,15 @@ const captcha = require('../../utils/captcha')
 const logger = require('../../utils/logger')(__filename)
 const productsClient = require('../../clients/products/products.client')
 const paymentLinkSession = require('../utils/payment-link-session')
-const { validateAmount } = require('../../utils/validation/form-validations')
+const formValidation = require('../../utils/validation/form-validations')
 const { convertPenceToPoundsAndPence } = require('../../utils/currency')
 const { AccountCannotTakePaymentsError } = require('../../errors')
 
 const HIDDEN_FORM_FIELD_ID_REFERENCE_VALUE = 'reference-value'
 const HIDDEN_FORM_FIELD_ID_AMOUNT = 'amount'
 const GOOGLE_RECAPTCHA_FORM_NAME = 'g-recaptcha-response'
 const ERROR_KEY_RECAPTCHA = 'recaptcha'
+const CONTACT_SERVICE_ZERO_VALUE_PAYMENT_ERROR = 'error.contactServiceForZeroValuePayment'
 
 function getBackLinkUrl (product, referenceProvidedByQueryParams, amountProvidedByQueryParams) {
   if (!product.price && !amountProvidedByQueryParams) {
@@ -106,13 +107,12 @@ async function postPage (req, res, next) {
   const sessionAmount = paymentLinkSession.getAmount(req, product.externalId)
   const referenceProvidedByQueryParams = paymentLinkSession.getReferenceProvidedByQueryParams(req, product.externalId)
   const amountProvidedByQueryParams = paymentLinkSession.getAmountProvidedByQueryParams(req, product.externalId)
-  const isPrefilledPayment = paymentLinkSession.getPrefilledFlag(req, product.externalId)
 
-  if (isPrefilledPayment !== 'false' &&
-    validateAmount(amountProvidedByQueryParams) &&
-    !validateAmount(amountProvidedByQueryParams).valid) {
-    const zeroAmountErrorMessagePath = 'error.contactServiceForZeroValuePayment'
-    return renderErrorView(req, res, zeroAmountErrorMessagePath, 400)
+  if (amountProvidedByQueryParams &&
+    formValidation.validateAmount(sessionAmount.toString()) &&
+    !formValidation.validateAmount(sessionAmount.toString()).valid
+  ) {
+    return renderErrorView(req, res, CONTACT_SERVICE_ZERO_VALUE_PAYMENT_ERROR, 400)
   }
 
   if (product.requireCaptcha) {

app/payment-links/confirm/confirm.controller.test.js

@@ -521,37 +521,72 @@ describe('Confirm Page Controller', () => {
         sinon.assert.calledWith(next, expectedError)
       })
 
-      it('when creating a payment returns a 403, should call next() with an AccountCannotTakePaymentsError', async () => {
-        req = {
-          correlationId: '123',
-          product,
-          body: {
-            amount: '1000'
+      it('when creating a prefilled payment link with an amount equals to £0.00, should render an error view with the correct message',
+        async () => {
+          req = {
+            correlationId: '123',
+            product,
+            body: {
+              amount: '0'
+            }
           }
-        }
 
-        res = {
-          redirect: sinon.stub()
-        }
+          res = {
+            setHeader: sinon.stub(),
+            status: sinon.stub(),
+            render: sinon.stub(),
+            locals: {
+              __p: sinon.stub()
+            }
+          }
 
-        const next = sinon.stub()
+          const next = sinon.stub()
 
-        const error = new Error('Failed to create payment.')
-        error.errorCode = 403
-        mockProductsClient.payment.create.rejects(error)
+          mockPaymentLinkSession.getReference.withArgs(req, product.externalId).returns('test invoice number')
+          mockPaymentLinkSession.getAmount.withArgs(req, product.externalId).returns(0)
+          mockPaymentLinkSession.getReferenceProvidedByQueryParams.withArgs(req, product.externalId).returns(true)
+          mockPaymentLinkSession.getAmountProvidedByQueryParams.withArgs(req, product.externalId).returns(true)
+          res.locals.__p.withArgs('paymentLinks.confirm.totalToPay').returns('Total to pay')
 
-        await controller.postPage(req, res, next)
+          await controller.postPage(req, res, next)
 
-        sinon.assert.calledWith(
-          mockProductsClient.payment.create,
-          'an-external-id',
-          1000
-        )
+          sinon.assert.calledWith(res.setHeader, 'Content-Type', 'text/html')
+          sinon.assert.calledWith(res.status, 400)
+          sinon.assert.calledWith(res.render, 'error', { message: 'error.contactServiceForZeroValuePayment' })
+        })
 
-        const expectedError = sinon.match.instanceOf(AccountCannotTakePaymentsError)
-          .and(sinon.match.has('message', 'Forbidden response returned by Public API when creating payment'))
-        sinon.assert.calledWith(next, expectedError)
-      })
+      it('when creating a payment returns a 403, should call next() with an AccountCannotTakePaymentsError',
+        async () => {
+          req = {
+            correlationId: '123',
+            product,
+            body: {
+              amount: '1000'
+            }
+          }
+
+          res = {
+            redirect: sinon.stub()
+          }
+
+          const next = sinon.stub()
+
+          const error = new Error('Failed to create payment.')
+          error.errorCode = 403
+          mockProductsClient.payment.create.rejects(error)
+
+          await controller.postPage(req, res, next)
+
+          sinon.assert.calledWith(
+            mockProductsClient.payment.create,
+            'an-external-id',
+            1000
+          )
+
+          const expectedError = sinon.match.instanceOf(AccountCannotTakePaymentsError)
+            .and(sinon.match.has('message', 'Forbidden response returned by Public API when creating payment'))
+          sinon.assert.calledWith(next, expectedError)
+        })
 
       it('should return 400 and redirect to reference page for CARD_NUMBER_IN_PAYMENT_LINK_REFERENCE_REJECTED error', async () => {
         req = {

app/payment-links/utils/payment-link-session.js

@@ -8,7 +8,6 @@ const AMOUNT_KEY = 'amount'
 const REFERENCE_PROVIDED_BY_QUERY_PARAMS_KEY = 'referenceProvidedByQueryParams'
 const AMOUNT_PROVIDED_BY_QUERY_PARAMS_KEY = 'amountProvidedByQueryParams'
 const ERROR_KEY = 'error'
-const PRE_FILLED_KEY = 'prefilled'
 
 function cookieIndex (key, productExternalId) {
   return `${getSessionCookieName()}.${productExternalId}.${key}`
@@ -56,13 +55,6 @@ function deletePaymentLinkSession (req, productExternalId) {
   lodash.unset(req, `${getSessionCookieName()}.${productExternalId}`)
 }
 
-function getPrefilledFlag (req, productExternalId) {
-  return lodash.get(req, cookieIndex(PRE_FILLED_KEY, productExternalId))
-}
-function setPrefilledFlag (req, productExternalId, prefilled) {
-  lodash.set(req, cookieIndex(PRE_FILLED_KEY, productExternalId), prefilled)
-}
-
 module.exports = {
   getReference,
   setReference,
@@ -72,7 +64,5 @@ module.exports = {
   getAmountProvidedByQueryParams,
   deletePaymentLinkSession,
   getError,
-  setError,
-  setPrefilledFlag,
-  getPrefilledFlag
+  setError
 }

locales/en.json

@@ -19,7 +19,7 @@
 		"default": "There’s a problem with the payments platform. Please try again later",
 		"internal": "Sorry, we’re unable to process your request. Try again later.",
 		"contactService": "Please contact the service you are trying to make a payment to.",
-		"contactServiceForZeroValuePayment": "Please contact the service regarding the zero amount payment error."
+		"contactServiceForZeroValuePayment": "There is a problem with the link you have been sent to use to pay. The payment amount cannot be £0.00. Contact the service you’re trying to make a payment to."
 	},
 	"404Page": {
 		"title": "Page not found",
@@ -82,7 +82,7 @@
 		},
 		"fieldValidation": {
 			"enterAnAmountInPounds": "Enter an amount of money to pay",
-			"enterANonZeroAmountInPounds": "Enter an amount that is £0.01 or more",
+			"enterANonZeroAmountInPounds": "Amount must be £0.01 or more",
 			"enterAnAmountInTheCorrectFormat": "Enter an amount in pounds and pence using digits and a decimal point, like 123.45 or 156.00",
 			"enterAnAmountUnderMaxAmount": "Enter an amount that is £100,000 or less",
 			"enterAReference": "You must enter your %s",