How to test chrome extensions?

Question

Is there a good way to do this? I'm writing an extension that interacts with a website as a content script and saves data using localstorage. Are there any tools, frameworks, etc. that I can use to test this behavior? I realize there are some generic tools for testing javascript, but are those sufficiently power to test an extension? Unit testing is most important, but I'm also interested in other types of testing (such as integration testing).

Answer 1

Yes, the existing frameworks are pretty useful..

In the recent past, I have placed all my tests on a "test" page that was embedded in to the application but not reachable unless physically typed.

For instance, I would have all the tests in a page accessible under chrome-extension://asdasdasdasdad/unittests.html

The tests would have access to localStorage etc. For accessing content scripts, in theory you could test that through embedded IFRAMEs in your test page, however these are more integration level testing, unit tests would require you to abstract that away from real pages so that you don't depend on them, likewise with access to localStorage.

If you want to test pages directly, you can orchestrate your extension to open new tabs (chrome.tab.create({"url" : "someurl"}). For each of the new tabs your content script should run and you can use your testing framework to check that your code has done what it should do.

As for frameworks, JsUnit or the more recent Jasmine should work fine.

Answer 2

Working on several chrome extensions I came up with sinon-chrome project that allows to run unit-tests using mocha, nodejs and phantomjs.

Basically, it creates sinon mocks of all chrome.* API where you can put any predefined json responses.

Next, you load your scripts using node's vm.runInNewContext for background page and phantomjs for render popup / options page.

And finally, you assert that chrome api was called with needed arguments.

Let's take an example:
Assume we have simple chrome extension that displays number of opened tabs in button badge.

background page:

chrome.tabs.query({}, function(tabs) {   chrome.browserAction.setBadgeText({text: String(tabs.length)}); }); 

To test it we need:

1. mock chrome.tabs.query to return predefined response, e.g. two tabs.
2. inject our mocked chrome.* api into some environment
3. run our extension code in this environment
4. assert that button badge equals to '2'

The code snippet is following:

const vm = require('vm'); const fs = require('fs'); const chrome = require('sinon-chrome');  // 1. mock `chrome.tabs.query` to return predefined response  chrome.tabs.query.yields([   {id: 1, title: 'Tab 1'},    {id: 2, title: 'Tab 2'} ]);  // 2. inject our mocked chrome.* api into some environment const context = {   chrome: chrome };  // 3. run our extension code in this environment const code = fs.readFileSync('src/background.js'); vm.runInNewContext(code, context);  // 4. assert that button badge equals to '2' sinon.assert.calledOnce(chrome.browserAction.setBadgeText); sinon.assert.calledWithMatch(chrome.browserAction.setBadgeText, {   text: "2" }); 

Now we can wrap it into mocha's describe..it functions and run from terminal:

$ mocha  background page   ✓ should display opened tabs count in button badge  1 passing (98ms) 

You can find full example here.

Additionally, sinon-chrome allows to trigger any chrome event with predefined response, e.g.

chrome.tab.onCreated.trigger({url: 'http://google.com'});