Sunday, July 24, 2011

The Double Sin of the Early Perfect Test Case

Since I started leading my current testing team, I’ve been struggling with the test case base.

There are a few factors that made the test case base clumsy and outdated. One of the most stunning facts for me was that even test cases that demonstrated big investment in details were often out dated. Despite the large investment, some details were wrong, had changed, had never been true, or were outdated. Often, you could find new testers struggling to understand and execute the test baseline.

The First Sin: Detailed Gen 0 Test Cases

In my experience when test cases are created before the test designer sees and experiences the product, it’s more than likely that they will not be accurate.

The reason for the failure is the limitation of our mind to perfectly imagine an abstract design. Sometimes even the designers doesn’t have a 100% complete design. While you can plan many things ahead of time, you can also anticipate that you will have gaps in your planning, but not anticipate their exact location.

The Second Sin: Detailed Gen 1 Test Cases

What about tests that successfully made it from Gen 0 to Gen 1 and proved to be correct? What about tests that were designed after the product was introduced and tried? They might not suffer from the first sin, but they will suffer from the second sin. Although these tests were accurate in the assumptions about the product itself, not all of them were the correct ones to run. Moreover, some of the tests that did a great job for Gen 1, finished their duty. Using these tests in regression will not be efficient.

As we progress with the test execution, we learn more about the risks of the product. At the end of the first generation testing we can plan better regression testing for the next generations. Typically we will add a small number of test cases and get rid of a larger amount of tests.

Conclusion: investing in too many detailed test cases during Gen0 and Gen1 is not efficient.

I’ll try to define basic guidelines to deal with this issue:

1) Lower the expectations from Gen0 and Gen 1 test cases – understand the built-in limitation of these test cases: Gen 0 might be inaccurate and Gen 1 will not fit your regression needs.

2) Seek for alternatives when planning Gen 0 and Gen 1 test cases. For example, use checklists instead of steps (See “The Value of Checklists and the Danger of Scripts” by Cem Kaner).

3) Try to thinks of better uses of your time during test planning. For example, invest in automation infrastructure during preparation.

4) Realize that moving from Gen 1 o Gen 2 will require more time in test documentation, and is not just copy-paste from Gen0-1 test cases. In this stage, you can save time by creating less “perfect” test cases of new features in the same product introduced at this time.

5) Consider the possibility that you will come to like your lean Gen 0 and Gen 1 test cases so much, that you won’t want to invest in more details for the regression test case base.

In case you claim that your experience is different and it’s possible to create perfect re-usable test plans in early stages, I can think of the following possibilities:

1) You are a better product and test designer than the ones I work with (please mentor me).

2) You don’t have complex and innovative products like the products that I test.

3) You follow a perfect process that prevents you from falling in such traps (and I would like to hear more about it).