Equivalence Partitioning

Equivalence partitioning is a software testing technique that involves dividing the input data of a software application into partitions of equivalent data from which test cases can be derived. The key idea is that each partition should represent a set of inputs that are treated similarly by the system, meaning they are expected to produce the same behavior and thus are considered equivalent. This method helps reduce the total number of test cases to a manageable level while maintaining effective coverage.

Steps in Equivalence Partitioning:

1. Identify the input domain: Determine the range of input data for the software.

2. Divide the input domain into partitions: Create groups or partitions where each group contains inputs that the software should handle in the same way. These partitions should include:

   • Valid partitions: Groups of input values that should be processed correctly.

   • Invalid partitions: Groups of input values that should be handled as errors.

3. Select test cases: Choose representative test cases from each partition. Typically, one value from each partition is selected for testing.

Example:

Consider a software application that accepts an integer input representing age and has the following requirements:

• The valid age range is 18 to 60 (inclusive).

• Values below 18 are considered too young.

• Values above 60 are considered too old.

Using equivalence partitioning, you would create the following partitions:

1. Valid partitions:

   • 18 to 60 (inclusive)

2. Invalid partitions:

   • Below 18

   • Above 60

From these partitions, you can select representative test cases:

• From the valid partition: One value such as 25 (since any value between 18 and 60 should be handled the same way).

• From the invalid partitions: One value below 18 (e.g., 10) and one value above 60 (e.g., 70).

Benefits of Equivalence Partitioning

• Efficiency: Reduces the number of test cases needed by grouping similar inputs together.

• Coverage: Ensures that all different categories of input are tested.

• Simplicity: Simplifies the process of test case design.

Limitations of Equivalence Partitioning

• May not catch all edge cases, particularly those that lie on the boundaries between partitions.

• Requires a good understanding of the input domain and the application's behavior to create effective partitions.

Equivalence partitioning is often used in combination with other testing techniques, such as boundary value analysis, to enhance test coverage and effectiveness.