Fix miscalculated preview 2PT charge in review (#1583)

https://eaflood.atlassian.net/browse/WATER-4849 When previewing the two-part tariff charge calculation for some licences, the business spotted that the value returned was more than expected. They have deduced it is because the preview is incorrectly flagging the licence as having a 'public water supply' and, therefore, adds the additional £141 charge to the calculation. This change corrects what data we send to the [Charging Module API](https://github.com/DEFRA/sroc-charging-module-api) to ensure we present the correct preview charge to users.
DEFRA · Dec 23, 2024 · 28d2b50 · 28d2b50
1 parent bb8eaa6
commit 28d2b50
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Showing 2 changed files with 90 additions and 10 deletions.
diff --git a/app/services/bill-runs/review/preview.service.js b/app/services/bill-runs/review/preview.service.js
@@ -95,7 +95,7 @@ function _transaction(reviewChargeReference) {
     supportedSourceName: chargeReference.supportedSourceName,
     // If `twoPartTariff` is `true` then `section127Agreement` must also be `true`
     twoPartTariff: section127Agreement,
-    waterCompanyCharge: chargeReference.waterCompanyCharge !== null,
+    waterCompanyCharge: !!chargeReference.waterCompanyCharge,
     waterUndertaker: reviewChargeVersion.reviewLicence.licence.waterUndertaker,
     winterOnly
   }

diff --git a/test/services/bill-runs/review/preview.service.test.js b/test/services/bill-runs/review/preview.service.test.js
@@ -19,6 +19,7 @@ const FetchReviewChargeReferenceService = require('../../../../app/services/bill
 const PreviewService = require('../../../../app/services/bill-runs/review/preview.service.js')
 
 describe('Bill Runs Review - Preview service', () => {
+  let calculateChargeRequestStub
   let reviewChargeReference
   let yarStub
 
@@ -42,7 +43,7 @@ describe('Bill Runs Review - Preview service', () => {
 
       describe('and the request to the Charging Module API succeeds', () => {
         beforeEach(async () => {
-          Sinon.stub(CalculateChargeRequest, 'send').resolves({
+          calculateChargeRequestStub = Sinon.stub(CalculateChargeRequest, 'send').resolves({
             succeeded: true,
             response: {
               info: {
@@ -66,14 +67,95 @@ describe('Bill Runs Review - Preview service', () => {
           })
         })
 
-        it('adds a flash message stating the example charge returned by the Charging Module API', async () => {
-          await PreviewService.go(reviewChargeReference.id, yarStub)
+        describe('for a charge reference with no additional charges (null)', () => {
+          it('makes the correct request to the Charging Module API', async () => {
+            await PreviewService.go(reviewChargeReference.id, yarStub)
+
+            const generatedTransaction = calculateChargeRequestStub.args[0][0]
+
+            expect(generatedTransaction).to.equal({
+              abatementFactor: 1,
+              actualVolume: 9.092,
+              adjustmentFactor: 1,
+              aggregateProportion: 0.333333333,
+              authorisedDays: 0,
+              authorisedVolume: 9.092,
+              billableDays: 0,
+              chargeCategoryCode: '4.6.5',
+              compensationCharge: false,
+              credit: false,
+              loss: 'high',
+              periodStart: '01-APR-2023',
+              periodEnd: '31-MAR-2024',
+              ruleset: 'sroc',
+              section127Agreement: true,
+              section130Agreement: false,
+              supportedSource: false,
+              supportedSourceName: null,
+              twoPartTariff: true,
+              waterCompanyCharge: false,
+              waterUndertaker: false,
+              winterOnly: false
+            })
+          })
 
-          const [flashType, bannerMessage] = yarStub.flash.args[0]
+          it('adds a flash message stating the example charge returned by the Charging Module API', async () => {
+            await PreviewService.go(reviewChargeReference.id, yarStub)
 
-          expect(yarStub.flash.called).to.be.true()
-          expect(flashType).to.equal('charge')
-          expect(bannerMessage).to.equal('Based on this information the example charge is £20.00')
+            const [flashType, bannerMessage] = yarStub.flash.args[0]
+
+            expect(yarStub.flash.called).to.be.true()
+            expect(flashType).to.equal('charge')
+            expect(bannerMessage).to.equal('Based on this information the example charge is £20.00')
+          })
+        })
+
+        describe('for a charge reference with additional charges ({})', () => {
+          beforeEach(async () => {
+            reviewChargeReference.chargeReference.supportedSourceName = 'Support me please'
+            reviewChargeReference.chargeReference.waterCompanyCharge = false
+          })
+
+          it('makes the correct request to the Charging Module API', async () => {
+            await PreviewService.go(reviewChargeReference.id, yarStub)
+
+            const generatedTransaction = calculateChargeRequestStub.args[0][0]
+
+            expect(generatedTransaction).to.equal({
+              abatementFactor: 1,
+              actualVolume: 9.092,
+              adjustmentFactor: 1,
+              aggregateProportion: 0.333333333,
+              authorisedDays: 0,
+              authorisedVolume: 9.092,
+              billableDays: 0,
+              chargeCategoryCode: '4.6.5',
+              compensationCharge: false,
+              credit: false,
+              loss: 'high',
+              periodStart: '01-APR-2023',
+              periodEnd: '31-MAR-2024',
+              ruleset: 'sroc',
+              section127Agreement: true,
+              section130Agreement: false,
+              supportedSource: true,
+              supportedSourceName: 'Support me please',
+              twoPartTariff: true,
+              waterCompanyCharge: false,
+              waterUndertaker: false,
+              winterOnly: false
+            })
+          })
+
+          it('adds a flash message stating the example charge returned by the Charging Module API', async () => {
+            await PreviewService.go(reviewChargeReference.id, yarStub)
+
+            const [flashType, bannerMessage] = yarStub.flash.args[0]
+
+            expect(yarStub.flash.called).to.be.true()
+            expect(flashType).to.equal('charge')
+            expect(bannerMessage).to.equal('Based on this information the example charge is £20.00')
+          })
         })
       })
 
@@ -106,8 +188,6 @@ describe('Bill Runs Review - Preview service', () => {
     })
 
     describe('for a review charge reference with a total allocation that is 0', () => {
-      let calculateChargeRequestStub
-
       beforeEach(() => {
         Sinon.stub(FetchReviewChargeReferenceService, 'go').resolves(reviewChargeReference)