From c20386d2968a868c56cfc3617984bc73ccf474b0 Mon Sep 17 00:00:00 2001
From: GTVJ <gwyn.jones@digital.cabinet-office.gov.uk>
Date: Fri, 7 Jun 2024 15:31:16 +0100
Subject: [PATCH] AUT-1466: Show end of telephone number on MFA resend screen

* includes the last three digits of a user's telephone number in
  the relevant template, making use of the returnLastCharacters
  Nunjucks filter
* introduces a new test to validate the last three digits of the
  user's telephone number are included in the response
* updates returnLastCharactersOnly to ensure an empty string will
  be returned if the function receives a non-string argument. I
  have done this because I found that is possible for the Nunjucks
  macro to receive a undefined value which it then passed to the
  function. If this happens, there would have been an error resulting
  in a 500.
---
 src/components/resend-mfa-code/index.njk           | 10 +++-------
 .../tests/resend-mfa-code-integration.test.ts      | 14 +++++++++++++-
 src/utils/phone-number.ts                          |  2 +-
 test/unit/utils/phone-number.test.ts               |  3 +++
 4 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/src/components/resend-mfa-code/index.njk b/src/components/resend-mfa-code/index.njk
index af60efa3e..3f7f376ab 100644
--- a/src/components/resend-mfa-code/index.njk
+++ b/src/components/resend-mfa-code/index.njk
@@ -6,13 +6,9 @@
 {% set showBack = true %}
 {% set hrefBack = 'enter-code' %}
 
-{% if isResendCodeRequest %}
-    {% set phoneNumberMessage %}
-       {{ 'pages.resendMfaCode.phoneNumber.isResendCodeRequest' | translate }} <span class='govuk-!-font-weight-bold'>{{ phoneNumber }}</span>
-    {% endset %}
-{% else %}
-    {% set phoneNumberMessage = 'pages.resendMfaCode.phoneNumber.default' | translate | replace("[mobile]", phoneNumber) %}
-{% endif %}
+{% set phoneNumberMessage %}
+   {{ 'pages.resendMfaCode.phoneNumber.isResendCodeRequest' | translate }} <span class='govuk-!-font-weight-bold'>{{ phoneNumber | returnLastCharacters({limit: 3}) }}</span>
+{% endset %}
 
 {% block content %}
     <form action="/resend-code" method="post" novalidate="novalidate">
diff --git a/src/components/resend-mfa-code/tests/resend-mfa-code-integration.test.ts b/src/components/resend-mfa-code/tests/resend-mfa-code-integration.test.ts
index b33cb46a5..66db89f88 100644
--- a/src/components/resend-mfa-code/tests/resend-mfa-code-integration.test.ts
+++ b/src/components/resend-mfa-code/tests/resend-mfa-code-integration.test.ts
@@ -1,6 +1,6 @@
 import request from "supertest";
 import { describe } from "mocha";
-import { sinon } from "../../../../test/utils/test-utils";
+import { expect, sinon } from "../../../../test/utils/test-utils";
 import nock = require("nock");
 import * as cheerio from "cheerio";
 import decache from "decache";
@@ -61,6 +61,18 @@ describe("Integration:: resend mfa code", () => {
 
   it("should return resend mfa code page", (done) => {
     request(app).get(PATH_NAMES.RESEND_MFA_CODE).expect(200, done);
+
+    it("should include the last three digits of the user's telephone number", (done) => {
+      request(app)
+        .get(PATH_NAMES.RESEND_MFA_CODE)
+        .expect(function (res) {
+          const $ = cheerio.load(res.text);
+          expect($(".govuk-inset-text").text()).to.eq(
+            "We will send a code to your phone number ending with 867"
+          );
+        })
+        .expect(200, done);
+    });
   });
 
   it("should return error when csrf not present", (done) => {
diff --git a/src/utils/phone-number.ts b/src/utils/phone-number.ts
index 493cd38ec..4186cce4a 100644
--- a/src/utils/phone-number.ts
+++ b/src/utils/phone-number.ts
@@ -60,5 +60,5 @@ export function returnLastCharactersOnly(
   value: string,
   options: { limit: number } = { limit: 4 }
 ): string {
-  return value.slice(-options.limit);
+  return value?.length ? value.slice(-options.limit) : "";
 }
diff --git a/test/unit/utils/phone-number.test.ts b/test/unit/utils/phone-number.test.ts
index 6fb2eedb6..fd044f888 100644
--- a/test/unit/utils/phone-number.test.ts
+++ b/test/unit/utils/phone-number.test.ts
@@ -252,5 +252,8 @@ describe("phone-number", () => {
         ).to.equal(i);
       });
     });
+    it("should return an empty string if passed empty string", () => {
+      expect(returnLastCharactersOnly("", { limit: 3 })).to.equal("");
+    });
   });
 });