Hunting the Shmoo

At the beginning of September, I was asked to write yet another automated test harness for testing user responsiveness. Among other things, the harness needed to be capable of automating a wide range of user interactions in Firefox (such as opening context menus, clicking buttons etc). Oh and by the way this needs to be finished as quickly as possible.

It turns out that machines aren’t very good at interacting with user interfaces designed for humans. Properly automating a complex piece of software like Firefox would take ages as there’s a whole plethora of things to think about. Luckily, at Mozilla we already have a tool for automating user interaction called Mozmill. The good news is that Mozmill’s driver is excellent at automating Firefox’s UI. The bad news is that the test harness piece is very bulky and unwieldy. Trying to use a Mozmill test to drive Firefox is just an unpleasant experience all around.

So rather than re-write a driver from scratch, or be stuck trying to shoehorn my test harness into Mozmill, I decided to do a little work and isolate Mozmill’s driver from Mozmill’s test harness. Unlike the test harness, Mozmill’s driver is lightweight and pure javascript (no python). I documented how to import the driver into an extension on MDN, but the end result is that any chrome scope JS can now import and use Mozmill’s driver. For example:

// Import mozmill and initialize a controller object  
Components.utils.import('resource://mozmill/driver/mozmill.js');  
let controller = getBrowserController();  
  
// Open google  
controller.open('http://www.google.com');  
controller.waitForPageLoad();  
  
// Type in the search box  
let textbox = findElement.ID(controller.tabs.activeTab, 'lst-ib');  
let button = findElement.Name(controller.tabs.activeTab, 'btnK');  
textbox.sendKeys('foobar');  
button.click();

Next Steps

The process for importing mozmill still isn’t as easy as I’d like. Ideally I’d like to have a Makefile that compiles all of the Mozmill driver files into a single ‘mozmill.js’ file similar to how jquery does it. If anyone has any experience or tips for getting something like this to work I’d appreciate it.