Pairwise Testing

Pairwise testing, also known as all-pairs testing, is a testing technique that aims to ensure that all possible pairs of input parameters are tested at least once. It is based on the observation that most software defects are triggered by interactions between pairs of input parameters, rather than interactions between larger sets of inputs. This method is highly effective in identifying defects while keeping the number of test cases manageable.

Benefits of Pairwise Testing:

• Efficiency: Reduces the number of test cases significantly compared to exhaustive testing.

• Effectiveness: Focuses on the most likely sources of defects by testing all possible pairs of input combinations.

• Cost-Effective: Saves time and resources while maintaining high coverage.

Steps to Implement Pairwise Testing:

• Identify Input Parameters: Determine all the input parameters and their possible values.

• Generate Pairwise Combinations: Use tools or algorithms to generate all possible pairs of input combinations.

• Create Test Cases: Develop test cases based on the generated pairs.

Example of Pairwise Testing:

Consider a scenario where a software application has three input parameters:

• Browser: Chrome, Firefox, Edge

• Operating System: Windows, macOS, Linux

• User Type: Admin, Guest

If you were to test every possible combination, you would have:

• 3 browsers × 3 operating systems × 2 user types = 18 combinations

However, in pairwise testing, you focus only on covering all possible pairs of input parameters, which reduces the total number of test cases.

Using pairwise testing, we generate test cases that ensure every possible pair of parameters is tested at least once. In this case, instead of testing all 18 combinations, we only need 9 test cases to achieve good coverage.

Here’s how the test cases could be structured:

• Test Case 1: Chrome, Windows, Admin

• Test Case 2: Chrome, macOS, Guest

• Test Case 3: Chrome, Linux, Admin

• Test Case 4: Firefox, Windows, Guest

• Test Case 5: Firefox, macOS, Admin

• Test Case 6: Firefox, Linux, Guest

• Test Case 7: Edge, Windows, Guest

• Test Case 8: Edge, macOS, Admin

• Test Case 9: Edge, Linux, Guest

In these 9 test cases, every pair of browser, operating system, and user type is covered, ensuring that critical interactions between the parameters are tested without the need to run all 18 possible combinations.

Pairwise testing allows you to cover the most important input interactions with a fraction of the test cases required for exhaustive testing. By using this technique, you can save time and resources while still achieving effective defect detection.