Add new format money with commas to presenters

app/presenters/base.presenter.js

@@ -129,6 +129,22 @@ function formatNumberAsMoney (value, includeSymbol = false) {
   return `${symbol}${value.toFixed(2)}`
 }
 
+/**
+ * Formats a number which represents a value in pounds as a money string with commas, for example, 2889 as '2,889.00'
+ *
+ * > Credit to https://stackoverflow.com/a/32154217/6117745
+ *
+ * @param {Number} value The value to display as currency. Assumed to be in pounds
+ * @param {Boolean} includeSymbol Whether to add the £ symbol to the start of the returned string
+ *
+ * @returns {string} The value formatted as a money string with commas with optional currency symbol
+ */
+function formatNumberAsMoneyWithCommas (value, includeSymbol = false) {
+  const symbol = includeSymbol ? '£' : ''
+
+  return `${symbol}${value.toLocaleString('en-GB', { minimumFractionDigits: 2 })}`
+}
+
 /**
  * Pads a number to a given length with leading zeroes and returns the result as a string
  *
@@ -152,5 +168,6 @@ module.exports = {
   formatLongDate,
   formatLongDateTime,
   formatNumberAsMoney,
+  formatNumberAsMoneyWithCommas,
   leftPadZeroes
 }

test/presenters/base.presenter.test.js

@@ -186,6 +186,26 @@ describe('Base presenter', () => {
     })
   })
 
+  describe('#formatNumberAsMoneyWithCommas()', () => {
+    const valueInPence = 1149.5
+
+    describe('when no £ symbol is requested', () => {
+      it('correctly returns the value as a money string with commas and no symbol, for example, 1,149.50', async () => {
+        const result = BasePresenter.formatNumberAsMoneyWithCommas(valueInPence)
+
+        expect(result).to.equal('1,149.50')
+      })
+    })
+
+    describe('when the £ symbol is requested', () => {
+      it('correctly returns the value as a money string with commas and a symbol, for example, £1,149.50', async () => {
+        const result = BasePresenter.formatNumberAsMoneyWithCommas(valueInPence, true)
+
+        expect(result).to.equal('£1,149.50')
+      })
+    })
+  })
+
   describe('#leftPadZeroes()', () => {
     it('correctly pads numbers', async () => {
       const number = 123