Q. Explain Equivalence Class Partitioning ?

Equivalence Class Partitioning: It is a method in black box testing. It is designed to reduce the number of test cases by dividing tests in such a way that the system is expected to act the same way for all tests of each equivalence partition. Test inputs are selected from every class. Each possible input belongs to one and only one equivalence partition. In another sense it is a method that can help you derive test cases. You recognize classes of input or output conditions. The rule is that every member in the class causes the same kind of behaviour of the system. In other sense the Equivalence Class Partitioning method creates sets of inputs or outputs that are handled in the same way by the application. Example If you are testing for an input box accepting numbers from 1 to 1000 then there is no utilize in writing thousand test cases for all 1000 valid input numbers plus other test cases for invalid data. Using correspondence partitioning method above test cases can be divided into three sets of input data called as classes. Every test case is a representative of respective class.