All Pairs Testing is taken as a pair wise testing which is an approach for testing the software using combinational method. It is a method which has all discrete combinations of the parameters involved. Consider that we have a piece of software which is to be tested and also has 10 input fields and 10 possible settings for each input field. There are 10^10 possible to be tested. An exhaustive testing is impossible even if we wish to test all combinations.
Consider an example,
We have an application with a simple list box with 10 elements (let us consider 0,1,2,3,4,5,6,7,8,9) with a checkbox, radio button, text box and also Ok button. The constraint for the text box is – it can accept values between 1 and 100. We have exhaustive combination values to be calculated.
List Box = 10
Check Box = 2
Radio Button = 2
Text Box = 100
Total Number of Test Cases using Cartesian Method: 10*2*2*100 = 4000
Total Number of Test Cases including Negative Cases will be > 4000
The thinking is to bring down the numbers of test cases. We have to try to find out the number of cases by using the different conventional software testing techniques. We will consider the list box values as 0. 0 is neither positive neither negative. Radio button and check box values will not be reduced, each one of them will have 2 combinations(either ON /OFF). The text box values which can be reduced into three inputs(valid integer, Invalid integer, Alpha special character). We might calculate the number the of cases by using the software testing technique which is 2*2*2*3 = 24. We can even reduce the cases by following steps like:
Step 1- We have to order the values such as like one of the most number of values is the first and least which is placed as the last variable.
Step 2- Start filling the table column. List box can take 2 values.
Step 3- The next column we have in discussion is check box. This check box will take 2 values.
Step 4- We have to make sure that we cover all combinations between list box and check box.
Step 5- we use the same strategy for verifying the radio button. It will take 2 values.
Step 6- We have to verify if all pair values will be covered as shown in the table
|Text Box||List Box||Check Box||Radio Button|
Benefits of pair wise testing technique:
All pairs testing comparably reduces time of testing, which controls the testing costs. Quality assurance team checks a subset of input/output values and not all will generate effective cost coverage. This technique is helpful where there are simply many possible configuration options and also combinations to run. Pairwise testing tools make this work easier. Many open source and free tools exist to generate pairwise values sets. The testers must inform that the tool about how application functions to these value sets which are to be effective.
The challenges of Pairwise testing:
These factors will limit the effectiveness of All pairs testing. It has unknown interdependencies of variables in the software which is being tested. It has unrealistic value combinations, or ones that doesn’t reflect the end user. Tests do not find any defects in the back-end processing engines or systems.