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Mistakes lead to the introduction of defects (also called bugs). As I personally am aware, like all human beings I can make mistakes at any point in time, no matter what I might be working on. So it is on projects, where the business analyst can put a defect into a requirements specification, a tester can put a defect into a test case, a programmer can put a defect into the code, a technical writer can put a defect into the user guide, and so forth. Any work product can and often will have defects because any worker can and will make mistakes!
Now, I like to drink good wine, and I’ve collected bottles from around the world on my travels. Some I’ve stashed away for years, waiting for the right time to drink them, which always comes sooner or later. Some of these bottles have gotten a lot more valuable over the years. Odd as this will sound, in just a few ways, bugs are like wine. They definitely get more expensive with age, taking more effort and thus incurring more cost the longer they are in the system. Also, sooner or later most bugs need to be fixed. However, it’s definitely not a good idea to leave bugs lying around—or perhaps crawling around—in a cellar, and they’re certainly not appetizing!
To celebrate completion of the update to Advanced Software Testing: Volume I, here is an excerpt of Chapter 3. This is the central chapter of the book, addressing test design techniques.
We start with the most basic of specification-based test design techniques, equivalence partitioning.
Conceptually, equivalence partitioning is about testing various groups that are expected to be handled the same way by the system and exhibit similar behavior. Those groups can be inputs, outputs, internal values, calculations, or time values, and should include valid and invalid groups. We select a single value from each equivalence partition, and this allows us to reduce the number of tests. We can calculate coverage by dividing the number of equivalence partitions tested by the number identified, though generally the goal is to achieve 100% coverage by selecting at least one value from each partition.
This technique is universally applicable at any test level, in any situation where we can identify the equivalence partitions. Ideally, those partitions are independent, though some amount of interaction between input values does not preclude the use of the technique. This technique is also very useful in constructing smoke tests, though testing of some of the less-risky partitions frequently is omitted in smoke tests. This technique will find primarily functional defects where data is processed improperly in one or more partitions. The key to this technique is to take care that the values in each equivalence partition are indeed handled the same way; otherwise, you will miss potentially important test values.
Since it is not possible to test everything, it is necessary to pick a subset of the overall set of tests to be run. Read this article to discover how quality risks analysis can help one focus the test effort.
Recorded February 16, 2017
Recorded April 7, 2016
Length: 0h 38m 45s
If you’ve been testing for any length of time, you know that the number of possible test cases is enormous if you try to test all possible combinations of inputs, configuration values, types of data, and so forth. It’s like the mythical monster, the many-headed Hydra, which would sprout two or more new heads for each head that was cut off. Two simple approaches to dealing with combinatorial explosions such as this are equivalence partitioning and boundary value analysis, but those techniques don’t check for interactions between factors. A reasonable, manageable way to test combinations is called pairwise testing, but to do it you’ll need a tool. In this inaugural One Key Idea session, Rex will demonstrate the use of a free tool, ACTS, built by the US NIST and available for download worldwide. We can’t promise to turn you into Hercules, but you will definitely walk away able to slay the combinatorial Hydra.
The Advanced Test Automation Engineer Boot Camp, created by Rex Black, past President of the International Software Testing Qualifications Board (ISTQB), past President of the American Software Testing Qualifications Board (ASTQB) and co-author of a number of International Software Testing Qualifications Board syllabi, is ideal for testers and test teams preparing for certification in a short timeframe with time and money constraints.
The Foundation Business Analyst Boot Camp, created by Rex Black, past President of the International Software Testing Qualifications Board (ISTQB), past President of the American Software Testing Qualifications Board (ASTQB) and co-author of a number of International Software Testing Qualifications Board syllabi, is ideal for testers and test teams preparing for certification in a short timeframe with time and money constraints.