Merge pull request #149 from RiyaJohn/screen-hdr

Fixes #138 Export screen details header for HMRC (Gov-Client-Screens)

USAGE.md

@@ -50,13 +50,13 @@ const {headerValue, error} = getGovClientBrowserDoNotTrackHeader();
 
 * To get Gov-Client-Timezone HMRC Fraud prevention header:
 ```js
-import getGovClientTimezoneHeader from 'user-data-for-fraud-prevention';
+import {getGovClientTimezoneHeader} from 'user-data-for-fraud-prevention';
 const {headerValue, error} = getGovClientTimezoneHeader();
 ```
 
 * To get Gov-Client-Local-IPs HMRC Fraud prevention header:
 ```js
-import getGovClientLocalIPsHeader from 'user-data-for-fraud-prevention';
+import {getGovClientLocalIPsHeader} from 'user-data-for-fraud-prevention';
 const {headerValue, error} = await getGovClientLocalIPsHeader();
 ```
 
@@ -65,3 +65,9 @@ const {headerValue, error} = await getGovClientLocalIPsHeader();
 import {getGovClientWindowSizeHeader} from 'user-data-for-fraud-prevention';
 const {headerValue, error} = getGovClientWindowSizeHeader();
 ```
+
+* To get Gov-Client-Screens HMRC Fraud prevention header:
+```js
+import {getGovClientScreensHeader} from 'user-data-for-fraud-prevention';
+const {headerValue, error} = getGovClientScreensHeader();
+```

src/js/hmrc/mtdFraudPrevention.js

@@ -185,3 +185,15 @@ export const getGovClientWindowSizeHeader = () => {
 };
 
 
+
+/**
+ * Returns the value for Gov-Client-Screens HMRC Fraud prevention header.
+ * @returns {object} with headerValue key having the value of the header or error key if there is an error
+ */
+export const getGovClientScreensHeader = () => {
+  try {
+    return {headerValue: getScreenData()};
+  } catch (error) {
+    return {error};
+  }
+}

src/js/index.ts

@@ -9,5 +9,6 @@ export {
   getGovClientDeviceID,
   getGovClientTimezoneHeader,
   getGovClientLocalIPsHeader,
-  getGovClientWindowSizeHeader
+  getGovClientWindowSizeHeader,
+  getGovClientScreensHeader
 } from './hmrc/mtdFraudPrevention';

tests/unit/hmrc/mtdFraudPrevention.test.js

@@ -19,6 +19,7 @@ import {getGovClientDeviceID} from "../../../src/js/hmrc/mtdFraudPrevention";
 import {getGovClientBrowserDoNotTrackHeader} from "../../../src/js/hmrc/mtdFraudPrevention";
 import {getGovClientTimezoneHeader} from "../../../src/js/hmrc/mtdFraudPrevention";
 import {getGovClientWindowSizeHeader} from "../../../src/js/hmrc/mtdFraudPrevention"
+import {getGovClientScreensHeader} from "../../../src/js/hmrc/mtdFraudPrevention";
 
 describe("FraudPreventionHeaders", () => {
   resetDeviceIpString();
@@ -372,3 +373,45 @@ describe("getGovClientWindowSizeHeader", () => {
 
 
 
+
+describe("GovClientScreensHeader", () => {
+  let screenSpy, windowSpy;
+
+  beforeEach(() => {
+    screenSpy = jest.spyOn(global, 'screen', 'get');
+    windowSpy = jest.spyOn(global, 'window', 'get');
+  });
+
+  afterEach(() => {
+    screenSpy.mockRestore();
+    windowSpy.mockRestore();
+  });
+
+  it("returns correct headerValue when there is no error",  () => {
+    screenSpy.mockImplementation(() => ({
+      width: 1019,
+      height: 1021,
+      colorDepth: 17,
+    }));
+
+    windowSpy.mockImplementation(() => ({
+      devicePixelRatio: 2,
+    }));
+
+    const {headerValue, error} = getGovClientScreensHeader();
+    expect(error).toBe(undefined);
+    expect(headerValue).toBe(`width=1019&height=1021&scaling-factor=2&colour-depth=17`);
+  });
+
+  it("returns error when there is an error",  () => {
+    screenSpy.mockImplementation(() => {throw Error("Something went wrong.")});
+
+    windowSpy.mockImplementation(() => ({
+      devicePixelRatio: 2,
+    }));
+
+    const {headerValue, error} = getGovClientScreensHeader();
+    expect(error).toEqual(Error("Something went wrong."));
+    expect(headerValue).toBe(undefined);
+  });
+});