How to regression test Web-based applications

The most important step in regression suites is planning ahead-- that way, you have the suite when you need it (which is usually in high-stress situations that require quick turnaround). In a previous ATE answer, I alluded to a few steps useful in identifying a regression test suite. I generally build my test suite from two types of cases: cases I run for every regression (priority 1 test cases which, if they fail, would cause a release to not ship) and cases I run with a focus on the change that's being introduced in the current release. The first suite of cases is pretty static; rarely do priorities change within a feature set. The second suite is more dynamic and is generally created shortly before the pass begins.

There aren't many steps I take which are unique to or special for Web application testing. The bigger key in selecting cases is to be familiar with your application and your development team. Know what their biggest weaknesses are -- not so you can accuse them, but because you need to test around those weaknesses. For instance, if a team has solid coding skills but is haphazard in packaging and deployment, gauge your regression test to spend time investigating the nuances introduced when your package is built and/or deployed.

One topic which comes up often in Web application regression is the browser platform. As new browser versions are introduced, compatibility can be affected. Typically, support for a new browser platform is considered a release work item, but what about backwards compatibility? If your team is adding the latest, greatest browser version to your test list but NOT removing anything, you'll need to keep that in mind. Often, changes between browser versions have backwards compatibility issues. Yet you can't regress every platform all the time. I take three steps to address this: first, I encourage my teams to rotate browsers during their day-to-day testing. Secondly, I select an older browser version with which to perform a deep dive regression during the regression pass. Finally, I "tune" my cases to my development teams' skills. If they're notoriously neglectful of a certain version of Internet Explorer, for example, I'll be sure to touch that browser version during my testing.