Equivalence
Partitioning
By: Khalifa, Husam Ali

Equivalence partitioning
 Equivalence partitioning is a software testing technique

that divides the input and/or output data of a software unit into partitions of data from which test cases can be derived.  The equivalence partitions are usually derived from the requirements specification for input attributes that influence the processing of the test object.

 Test cases are designed to cover each partition at least once. Using equivalence partitioning
• Equivalence partitioning technique uncovers classes of errors.

• Testing uncovers sets of inputs that causes errors or failures, not just individual inputs.

What can be partitioned?
 Usually it is the input data that is partitioned.
 However, depending on the software unit to be tested, output data can be partitioned as well.

 Each partition shall contain a set or range of values, chosen such that all the values can reasonably be expected to be treated by the component in the same way (i.e. they may be considered ‘equivalent’).

Defining Partitions
A number of items must be considered:

 All valid input data for a given condition are likely to go through the same process.

 Invalid data can go through various processes and need to be evaluated more carefully. For example:
 a blank entry may be treated differently than an incorrect entry,
 a value that is less than a range of values may be treated differently

than a value that is greater,
 if there is more than one error condition within a particular function, one error may override the other, which means the subordinate error does not get tested unless the other value is valid.

Equivalence partitioning example
• Example of a function which takes a parameter
“month”.

• The valid range for the month is 1 to 12, representing January to