Update the view return version presenter

Didn't spot at the time it was doing it's won implementation of `formatAbstractionPeriod()`. So, we update it to use the common one in `base.presenter.js`.

We also didn't spot it was using the legacy pattern, of sometimes prefixing dates with `From ...`. Again, using the common method in the base presenter helps us stick to a common pattern.

app/presenters/return-versions/view.presenter.js

@@ -5,7 +5,7 @@
  * @module ViewPresenter
  */
 
-const { formatAbstractionDate } = require('../base.presenter.js')
+const { formatAbstractionPeriod } = require('../base.presenter.js')
 const { formatLongDate } = require('../base.presenter.js')
 const { isQuarterlyReturnSubmissions } = require('../../lib/dates.lib.js')
 const { returnRequirementReasons, returnRequirementFrequencies } = require('../../lib/static-lookups.lib.js')
@@ -39,13 +39,14 @@ function go(returnVersion) {
 }
 
 function _abstractionPeriod(requirement) {
-  const { abstractionPeriodStartDay, abstractionPeriodStartMonth, abstractionPeriodEndDay, abstractionPeriodEndMonth } =
-    requirement
-
-  const startDate = formatAbstractionDate(abstractionPeriodStartDay, abstractionPeriodStartMonth)
-  const endDate = formatAbstractionDate(abstractionPeriodEndDay, abstractionPeriodEndMonth)
+  const abstractionPeriod = formatAbstractionPeriod(
+    requirement.abstractionPeriodStartDay,
+    requirement.abstractionPeriodStartMonth,
+    requirement.abstractionPeriodEndDay,
+    requirement.abstractionPeriodEndMonth
+  )
 
-  return `From ${startDate} to ${endDate}`
+  return abstractionPeriod ?? ''
 }
 
 function _agreementsExceptions(returnRequirement) {

test/presenters/return-versions/view.presenter.test.js

@@ -16,7 +16,7 @@ const ReturnVersionModel = require('../../../app/models/return-version.model.js'
 // Thing under test
 const ViewPresenter = require('../../../app/presenters/return-versions/view.presenter.js')
 
-describe('Return Versions - View presenter', () => {
+describe.only('Return Versions - View presenter', () => {
   let returnVersion
 
   beforeEach(() => {
@@ -39,7 +39,7 @@ describe('Return Versions - View presenter', () => {
       reason: 'New licence',
       requirements: [
         {
-          abstractionPeriod: 'From 1 April to 31 October',
+          abstractionPeriod: '1 April to 31 October',
           agreementsExceptions: 'None',
           frequencyCollected: 'monthly',
           frequencyReported: 'monthly',
@@ -205,12 +205,29 @@ describe('Return Versions - View presenter', () => {
 
   describe('the "requirements" property', () => {
     describe('the requirements "abstractionPeriod" property', () => {
-      it('formats the abstraction period for display', () => {
-        const result = ViewPresenter.go(returnVersion)
+      describe('when the abstraction period has been set', () => {
+        it('formats the abstraction period for display', () => {
+          const result = ViewPresenter.go(returnVersion)
+
+          const { abstractionPeriod } = result.requirements[0]
+
+          expect(abstractionPeriod).to.equal('1 April to 31 October')
+        })
+      })
 
-        const { abstractionPeriod } = result.requirements[0]
+      describe('when the abstraction period has not been set', () => {
+        beforeEach(() => {
+          returnVersion.returnRequirements[0].abstractionPeriodEndDay = null
+          returnVersion.returnRequirements[0].abstractionPeriodEndMonth = null
+          returnVersion.returnRequirements[0].abstractionPeriodStartDay = null
+          returnVersion.returnRequirements[0].abstractionPeriodStartMonth = null
+        })
+
+        it('returns an empty string', () => {
+          const result = ViewPresenter.go(returnVersion)
 
-        expect(abstractionPeriod).to.equal('From 1 April to 31 October')
+          expect(result.requirements[0].abstractionPeriod).to.equal('')
+        })
       })
     })