Testing the passive view layer is a technical challenge. We not only need to find a way for our test to inject native events into the browser to simulate user interaction, but we also need to be able to inspect the DOM elements and inject and execute scripts. This was very challenging to do approximately 5 years ago. In fact, it was considered complex and expensive, and some practitioners recommended not to test the passive view. After all, this layer is very thin and mostly contains the bindings of the UI to the HTML DOM, so the risk of error is not supposed to be high, specially if we use modern cross-browser frameworks to implement this layer.

Nonetheless, nowadays the technology has evolved, and we can do this kind of testing without much fuss if we use the right tools. One of these tools is Selenium 2.0 (also known as WebDriver) and its library for JavaScript, which is WebDriverJS (https://code.google.com/p/selenium/wiki/WebDriverJs).