Merge pull request #31 from Microsoft/caabreut/unit-tests

Add unit tests for some of the extension's 'backend' functionality

jest.config.js

@@ -30,7 +30,8 @@ module.exports = {
 
   // An array of regexp pattern strings used to skip coverage collection
   coveragePathIgnorePatterns: [
-    '\\\\node_modules\\\\'
+    '\\\\node_modules\\\\',
+    'index.js'
   ],
 
   // A list of reporter names that Jest uses when writing coverage reports

src/content/injectScript.js

@@ -4,6 +4,10 @@
  * @param {string} filepath - The filepath to the script to be injected.
  */
 function injectScript (filepath) {
+  if (filepath == null) {
+    throw Error('filepath must not be null or undefined');
+  }
+
   const bodyTag = document.getElementsByTagName('body')[0];
   const scriptTag = document.createElement('script');
   scriptTag.setAttribute('type', 'text/javascript');

src/content/injectScript.test.js

@@ -0,0 +1,25 @@
+import injectScript from './injectScript';
+
+describe('injectScript.js', () => {
+  it('should throw an Error when the filepath parameter is null', () => {
+    expect(() => injectScript(null)).toThrow();
+  });
+
+  it('should throw an Error when the filepath parameter is undefined', () => {
+    expect(() => injectScript(undefined)).toThrow();
+  });
+
+  it('should inject the code from the provided filepath into document.body as a script tag', () => {
+    document.body.innerHTML = '';
+
+    const filepath = 'some/file/path';
+    const expected = document.createElement('script');
+    expected.src = filepath;
+    expected.setAttribute('type', 'text/javascript');
+    expected.setAttribute('src', filepath);
+
+    injectScript('some/file/path');
+
+    expect(document.body.childNodes[0]).toEqual(expected);
+  });
+});

src/content/messaging/forwardTimingEvent.js

@@ -5,6 +5,18 @@
  * @listens CustomEvent
  */
 function forwardTimingEvent (timingEvent) {
+  if (timingEvent == null) {
+    throw Error('timingEvent must not be null or undefined');
+  }
+
+  if (!(timingEvent instanceof CustomEvent)) {
+    throw Error('timingEvent must be an instance of CustomEvent');
+  }
+
+  if (timingEvent.detail == null) {
+    throw Error('timingEvent.detail must not be null or undefined');
+  }
+
   chrome.runtime.sendMessage({
     action: 'timing',
     payload: timingEvent.detail

src/content/messaging/forwardTimingEvent.test.js

@@ -0,0 +1,55 @@
+import forwardTimingEvent from './forwardTimingEvent';
+
+describe('forwardTimingEvent.js', () => {
+  beforeAll(() => {
+    global.chrome = {
+      runtime: {
+        sendMessage: jest.fn()
+      }
+    };
+  });
+
+  it('should throw an Error when the timingEvent parameter is null', () => {
+    expect(() => forwardTimingEvent(null)).toThrow();
+  });
+
+  it('should throw an Error when the timingEvent parameter is undefined', () => {
+    expect(() => forwardTimingEvent(undefined)).toThrow();
+  });
+
+  it('should throw an Error when the timingEvent parameter is not an instance of CustomEvent', () => {
+    const input = { name: 'not a CustomEvent' };
+    expect(() => forwardTimingEvent(input)).toThrow();
+  });
+
+  it('should throw an Error when the timingEvent parameter\'s detail property is null', () => {
+    const input = new CustomEvent('timing', { detail: null });
+    expect(() => forwardTimingEvent(input)).toThrow();
+  });
+
+  it('should throw an Error when the timingEvent parameter\'s detail property is undefined', () => {
+    const input = new CustomEvent('timing');
+    expect(() => forwardTimingEvent(input)).toThrow();
+  });
+
+  it('should send the requested message via chrome.runtime', () => {
+    const expectedTimingEvent = new CustomEvent('timing', {
+      detail: { a: 1, b: 2, c: 3 }
+    });
+    const expectedMessage = {
+      action: 'timing',
+      payload: expectedTimingEvent.detail
+    };
+
+    // Has side-effects
+    forwardTimingEvent(expectedTimingEvent);
+
+    // Verify that chrome.runtime.sendMessage was only called once
+    // with a single argument: the expectedMessage object
+    expect(global.chrome.runtime.sendMessage.mock.calls).toEqual([[expectedMessage]]);
+  });
+
+  afterAll(() => {
+    delete global.chrome;
+  });
+});

src/content/messaging/sendSimpleMessage.js

@@ -3,6 +3,10 @@
  * @param {string} action - The value indicating the meaning of the message.
  */
 function sendSimpleMessage (action) {
+  if (action == null) {
+    throw Error('action must not be null or undefined');
+  }
+
   chrome.runtime.sendMessage({
     action: action
   });

src/content/messaging/sendSimpleMessage.test.js

@@ -0,0 +1,37 @@
+import sendSimpleMessage from './sendSimpleMessage';
+
+describe('sendSimpleMessage.js', () => {
+  beforeAll(() => {
+    global.chrome = {
+      runtime: {
+        sendMessage: jest.fn()
+      }
+    };
+  });
+
+  it('should throw an Error when the action parameter is null', () => {
+    expect(() => sendSimpleMessage(null)).toThrow();
+  });
+
+  it('should throw an Error when the action parameter is undefined', () => {
+    expect(() => sendSimpleMessage(null)).toThrow();
+  });
+
+  it('should send the requested message via chrome.runtime', () => {
+    const expectedAction = 'abc';
+    const expectedMessage = {
+      action: expectedAction
+    };
+
+    // Has side-effects
+    sendSimpleMessage(expectedAction);
+
+    // Verify that chrome.runtime.sendMessage was only called once
+    // with a single argument: the expectedMessage object
+    expect(global.chrome.runtime.sendMessage.mock.calls).toEqual([[expectedMessage]]);
+  });
+
+  afterAll(() => {
+    delete global.chrome;
+  });
+});

src/inject/messaging/sendEventViaDocument.js

@@ -3,6 +3,14 @@
  * @param {CustomEvent} event - The event to dispatch via the document.
  */
 function sendEventViaDocument (event) {
+  if (event == null) {
+    throw Error('event must not be null or undefined');
+  }
+
+  if (!(event instanceof CustomEvent)) {
+    throw Error('event must be an instance of CustomEvent');
+  }
+
   // This call to setTimeOut with 0 delay schedules this call to occur after
   // already existing events in the browser's queue, which includes rendering events.
   // This is to minimize the performance impact on the page due to the extension.

src/inject/messaging/sendEventViaDocument.test.js

@@ -0,0 +1,23 @@
+import sendEventViaDocument from './sendEventViaDocument';
+
+describe('sendEventViaDocument.js', () => {
+  beforeEach(() => {
+    jest.useFakeTimers();
+    document.dispatchEvent = jest.fn();
+  });
+
+  it('should throw an error when the event parameter is null', () => {
+    expect(() => sendEventViaDocument(null)).toThrow();
+  });
+
+  it('should throw an error when the event parameter is undefined', () => {
+    expect(() => sendEventViaDocument(undefined)).toThrow();
+  });
+
+  it('should throw an Error when the event parameter is not an instance of CustomEvent', () => {
+    const input = { name: 'not a CustomEvent' };
+    expect(() => sendEventViaDocument(input)).toThrow();
+  });
+
+  // TODO: need to figure out how to properly mock and spy on setTimeOut and its callback
+});