All texts are written by the texter according to a certain algorithm, which is stored in his head. This technique is not entirely convenient, and tedious. It would be nice if this algorithm was stored not in the head of the texter, but in a special code represented by some software. That is, you need to create a program that would automatically use the test – cases. That’s exactly what the pairwise testing method does.
As an example, you can take the option of testing the operation of a certain Internet resource, when using different browsers. In this case, it is important for us to know which of them our site will work better, with which worse, and under what conditions a failure can occur at all. To do this, you will have to use a lot of parameters, and, in various combinations. This will take a long time, not to mention a huge number of tests. But if you use the pairwise testing method, the number of tests will decrease many times.
The meaning of pairwise testing is that most of the documents describing the sequence of actions of the texter will be determined by a special test that automatically checks the combination of two different parameters. This eliminates errors that may occur if three or more parameters are combined. In this case, the texter himself chooses a set of cases, with the desired combination of parameters.
The complexity of this method is to choose an algorithm of actions that would provide a minimum number of tests, and at the same time would allow you to combine the pairs being tested in the same test. Well, for this you can use mathematical methods, which, for example, include orthogonal matrices.
To the uninitiated, this method will seem quite complicated. It will not be easy to understand it. This is its main danger. Even if you try to test the minimum number of parameters, it does not make the task easier. The complexity of the method will grow in proportion to the increase in the number of tested parameters. In addition, this method will give a positive result only if it is filled with properly selected functional tests. That is, if you want to test the site on different browsers, then, first of all, you need to make sure that on this operating system they will be quite capable of working with the default settings. With pair testing, a large number of parameters will be used that are different from those that were used by default, so there is a possibility of system failure, and at the same time the difficulty of localizing the parameter that caused it. In this case, the method will not work effectively, and it must be abandoned.
The conclusion is simple. The method of pairwise testing can be used only on a stable system, and only if the previous tests have lost their relevance.
Before choosing parameters for testing, you need to make sure that there are no negative tests, because when they are included in the test, only one parameter will be checked, which means that some pairs will not be taken into account and not checked at all. This is another drawback of this method.
The danger lies in the fact that the tester may simply not include in the case some important parameter or its value. In this case, the number of tests will automatically increase, which will lead to incorrect testing.
It is extremely difficult to conduct pairwise testing without the use of technical means. This can only be done with the help of special software products, such as, for example, “Allpairs”. But that’s a whole other topic.