I’ve recently been reading through my ISEB Practitioner notes, which I got when attending a course organised by Grove Consultants a few years back, as I mentioned in my previous post. It’s got me thinking about test cases, and in particular the four criteria of a good test case. Having attended both Rapid Software Testing and Rapid Test Management recently, and having rolled out an Exploratory and Session Based Test Strategy in my teams then it’s caused me to question again the validity of test cases and the need for them.

So, to a good test case. Reading my notes, a good test case is, in no particular order, apparently:

1. Exemplary.
2. Evolvable.
3. Economic.
4. Effective.

Straight from the ISTQB/ ISEB of course. But not without merit. Are these still relevant?

Exemplary

Good test cases can test more than one condition at the same time. This is one good reason for taking the time to design test cases in the first place. Just writing test cases because “it’s the done thing” or “because the policy says so” is time wasting, but designing them so that when the testing is carried out it is done so in the most efficient way requires exemplary test cases and can add value. It is also the case that test cases are shared and it’s difficult, especially in large organisations, to ensure that all testers have the same basic level of ability. Having test cases can help.

Evolvable

From a contextual point of view perhaps a good test case is not written down at all but merely in the testers head, and driving the testing into particular areas that the tester feels are worthy of time and effort. Cases where the software is the specification are becoming increasingly common; in-sufficient or non-existent requirements documentation which requires the tester to apply their previous knowledge of the system under test in order to effectively test it. Clearly in this case, if documented test cases are required then they will be need to evolve. As Rapid Software Testing mentions “How do you invent the right tests at the right time – evolve them with an exploratory strategy”.

Economic

Time is money and often in testing we have little time and sometimes little money. So using that time and that money in the most efficient way means we minimise the economic impact. Of course, sometimes the best way to get maximum value is to have a purely exploratory approach and spend more of the time and money with the software in hand. A choice which is key to a good test strategy and highly dependant on the industry area one is testing within.

Effective

Clearly a good test cases should be effective. We are not in the business of wasting time, particularly when time is precious as it often is in testing projects.

I’d argue that the definitions given in ISEB/ ISTQB are still relevant and can be a good guide as to what is required of a test case. In a lot of industries test cases are still very much required and, particularly where there is strict regulation such as in areas of financial software and even in mobile software. The ability to write a good test case is a skill which should not be forgotten.