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Resources for “Equivalence Partitioning”


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.

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Podcast Episodes

One Key Idea: Pairwise Testing Using ACTS 2/16/17

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.

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Black-box Bug-a-thon

If you are looking to spend one day learning powerful test techniques in a hands-on way using real apps, and having fun while doing so in a friendly yet competitive setting, this black-box bug-a-thon is for you.

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