Testability: A way to enhance your product's Utility Value

Testability to me is a feature of the product that makes it testable (a synonym for “usable”) in multiple contexts and ways. A mature testing process would always vouch for building testability right into the product during design stage where the developers are more willing and accommodating to accept “requests” from testers.

Typically only bugs make developers to listen to testers. Another important use of testability is that it makes “Test automation” more easy and efficient. Testers while doing automation need not spend hours and hours to create custom code to verify a test which could have been implemented as test hook – say a log file or a registry entry or database record or a status bar text. Ask for a test hook.

Just to give an example – I was looking at an automation idea where the test was to kick off a batch file and wait for it complete and then based on the result of the batch file, automation script would proceed. The problem the team was facing is how to make wait for script to finish. One option given by a tool vendor is to use a wait commend with some hard coded wait period.

Here is where stuck this idea of testability feature. I simply asked the developer to include a feature/task of creating an empty text file or registry entry to mark the end of batch processing. Developer happily included that feature which made our “wait” task easier and efficient than putting a dumb wait(100) kind of command. Another example of test hook is command line interfaces or APIs to product features that are typically driven with GUI. This will ease automation script maintenance when GUI unstable or changing.

One more example. We were planning to automate a feature where user would fill-out a form with lots of data which eventually would be submitted to web server in the form of an XML file. We wanted to simulate a load on web server by submitting a large number of such forms in a given span of time. When we asked the developer for help, he said that feature it not available. Then, we asked the development team for an API that would take the path to an XML file as the parameter and submit the contents of the file to web server to simulate form submission from client end. This made whole of automation work easy. Later on this testability feature was extended to include many interesting test hooks to make the job of testing easy.

Michael Hunter talks about testability at his blog – makes a good reading.