When we think of GUI-level test automation, we usually think of taking some sort of test case, designing a script with a language like Perl, Ruby or a vendor testing tool, and developing the test case programatically from beginning to end. The prevailing view is often that there is some sort of manual test case that we need to repeat, so we automate it in its entirety with a tool. This is a shallow view of test automation as James Bach, Bret Pettichord, Cem Kaner, Brian Marick and others have pointed out. I prefer the term “Computer Assisted Testing” (I believe coined by Cem Kaner) over “test automation” for this reason.
While developing automated tests, an interesting side effect came out in my development efforts. While I was debugging script code, I would run a portion of a test case many times. This would be a sequence of events; not an entire test case. I started to notice behavior changes from build to build when I watched a series of steps play back on my screen. When I would investigate, I found bugs that I may not have discovered doing pure manual testing, or running unattended automated tests. I started keeping snippets of scripts around to aid in exploratory testing activities, and found them very useful as another testing tool.
There are some benefits to automating a sequence of steps and blending this type of testing with manual testing. For example, if a test case has a large number of steps required to get to the area we want to focus testing on, using a script to automate that process helps us get there faster, frees us from distractions and helps us focus on the feature or unit under test. Humans get tired repeating tasks over and over and are prone to error. If precision is needed, computers can be programmed to help us. We can also test the software in a different way using a tool. We can easily control and vary test inputs, and measure what was different from previous test runs when bugs are discovered.
There are certain tasks that a human can do much better than a computer when it comes to testing. As James Bach says, testing is an interactive, cognitive process. Human reasoning and inference simply cannot be programmed into a test script, so the “test automation” notion will not replace a tester. Blending the investigative skills and natural curiousity of a tester with a tool that helps them discover bugs is a great way to focus some test automation efforts.
If you think of your automation efforts as “Computer Assisted Testing”, many more testing possibilities will come to mind. You just might harness technology in a more effective way, and it will show in your testing efforts.