CG: Why did you invent Selenium? What was the motivation?
Huggins: Selenium was extracted from a web-based (Python + Plone!) time-and-expense (T&E) application my team and I were building for my previous employer. One of the mandates for the new T&E app was that it needed to be "fast, fast, fast." The legacy application was a client-server Lotus Notes application and wasn't scalable to the current number of offices and employees at the time. To live up to the "fast, fast, fast" design goal, we tried to improve and speed up the user experience as much as possible. For example, expense reports can get pretty long for people who travel a lot. No matter how many default rows we put in a blank expense form, people often needed to add more rows of expense items to their reports. So we added an "Add row" button to the expense report form. To make this "fast, fast, fast," I decided to use a button that triggered JavaScript to dynamically add one blank row to the form. At the time (Spring 2004), however, JavaScript was considered buggy and evil by most web developers, so I caught a lot of flak for not going with the classic approach of POSTing the form and triggering a complete page refresh with the current form data, plus one blank row.
Going down the road of using JavaScript had consequences. For one, we had a really, really difficult time testing that little "Add row" button. And sadly, it broke often. One week "Add row" would be working in Mozilla (Firefox was pre-1.0), but broken in Internet Explorer. And of course, nothing was working in Safari since few developers were allowed to have Macs. ;-) The following week, we'd open a bug saying "'Add row' is broken in IE!!" The developer assigned to the issue would fix and test it in IE, but not test for regressions in Mozilla. So, "Add row" would now be broken in Mozilla, and I'd have to open a ticket saying "'Add row' is now broken in Mozilla!!!". Unlike most other corporate IT shops, we didn't have the luxury of telling all employees to use a single browser, and developers didn't want to manually test every feature in all supported browsers every time. Also, we had a very tiny budget and commercial testing tools were -- and still are -- ridiculously over-priced on a per-seat basis. The T&E project was done the "Agile Way" -- every developer does testing -- so shelling out thousands of dollars per developer for a testing tool wasn't going to happen. Never mind the fact that there were no commercial tools that did what we needed anyway!
After many months of trial and error and various code workarounds, I came to the conclusion I needed a testing tool that would let me functional-test JavaScript-enhanced web user interfaces (aka "DHTML" or now "Ajax"). More specifically, I needed to test the browser UIs: Internet Explorer, Mozilla Firefox, and Safari. There were no commercial apps at the time that could do this, and the only open source option was JsUnit, which was more focused on unit testing pure JavaScript functions, rather than being a higher-level black-box/smoke-test walk through a web app. So we needed to write our own tool. Our first attempt was a Mozilla extension called "driftwood" (never released), coded by Andrew McCormick, another co-worker of mine at the time. It did make testing the "Add row" button possible, but since it was Mozilla-only, it wasn't what we needed for testing in all browsers. Paul Gross and I started over, and I started to educate myself on functional testing tools and techniques and stumbled upon Ward Cunningham's Framework for Integrated Testing (FIT). I originally set out to implement "FIT for JavaScript," but quickly realized we were drifting away from the FIT API, so Selenium became its own thing.
CG: Why does the world need another test tool?
Huggins: At the time I created Selenium, had there been another testing tool that could test JavaScript UI features in all browsers on all platforms, believe me, I would have saved lots of time *not* writing my own tool.
CG: What's special about it?
Huggins: Well, maybe the right question is "What's “lucky” about it? Selenium was created in a time when JavaScript was considered "bad" and generally avoided by most professional web developers. Then Google Maps hit the scene a year later, the term "Ajax" was coined, and BOOM! Overnight, JavaScript became "good." Also, Firefox started stealing market share from IE. The combination of needing to test 1) JavaScript features 2) in several browsers (not just IE) was a "right place, right time" moment for Selenium.
CG: When did you realize that Selenium was a big deal? What was the tipping point?
Huggins: When I started being asked to give presentations or write about Selenium by people I didn't know. The tipping point for Selenium technically relied on two things: 1) the Selenium IDE for Firefox, written by Shinya Kasatani, which made installation and the first-hour experience tons better for new users. And 2), Selenium Remote Control (RC) created by Paul Hammant, and extended by Dan Fabulich, Nelson Sproul, and Patrick Lightbody, which let developers write their tests in Java, C#, Perl, Python, or Ruby, and not have to write all their tests in the original FIT-like HTML tables. Socially, if Google Maps or Gmail never existed and thus the whole Ajax gold rush, I wonder if JavaScript would still be considered "bad," with a similar "why bother?" attitude to testing it.
CG: Have you discovered any interesting teams using Selenium in ways you'd never intended?
Huggins: At my previous company, I did see some developers write Selenium scripts to create their time and expense reports for them from YAML or XLS files. Since we hadn't exposed a back-end API, automating the browser for data entry was the next best thing. It was never designed for this purpose, but I started (ab)using it as coded bug reports. Asking users for steps on how to reproduce a bug naturally lends itself to looking like a Selenium test for that bug. Also, I've used the Selenium IDE Firefox plug-in to enter NBC's "Deal or No Deal" contest on their website from home, but I stopped doing that when I read in the fine print that the use of automation tools to enter their contest was grounds for disqualification.
CG: What advice do you have to offer Google groups interested in Selenium?Huggins: Well, one of the biggest drawbacks with user interface testing tools is that they're slow for various reasons. One way to bring the test run times down is to run them in parallel on a grid of servers, instead of sequentially. Of course, that isn't news to your average Googler. Engineers would be more likely to run automated browser UI tests if they could run 1000 tests in 1 minute total time on 1000 machines instead of 1000 tests in 1000 minutes on 1 machine. Sadly, though, most projects allocate only one machine, maybe two, to browser testing. I'm really excited to come to Google with the resources, the corporate interest, and the internal client base to make a large scale Selenium UI test farm possible. Eventually, I’d like to take Selenium in some new directions that we’ll talk about in later blog posts. But I'm getting ahead of myself. I have to survive Noogler training first.
