This method categorizes the inputs and outputs of a class in order to test them separately. This minimizes the number of test cases that have to be designed.

To determine the different categories to test, partitioning can be broken down as follows:

- State-based partitioning - categorizes class operations based on how they change the state of a class

- Attribute-based partitioning - categorizes class operations based on attributes they use

- Category-based partitioning - categorizes class operations based on the generic function the operations perform