Ans. Equivalence Class Partitioning: It is a technique in black box testing. It is designed to minimize 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 each class. Every possible input belongs to one and only one equivalence partition." In another words it is a method that can help you derive test cases. You identify classes of input or output conditions. The rule is that each member in the class causes the same kind of behaviour of the system. In other words, the "Equivalence Class Partitioning" method creates sets of inputs or outputs that are handled in the same way by the application. E.g.: If you are testing for an input box accepting numbers from 1 to 1000 then there is no use in writing thousand test cases for all 1000 valid input numbers plus other test cases for invalid data. Using equivalence partitioning method above test cases can be divided into three sets of input data called as classes. Each test case is a representative of respective class.
Boundary Value Analysis: It’s widely recognized that input values at the extreme ends of input domain cause more errors in system. More application errors occur at the boundaries of input domain. ‘Boundary value analysis’ testing technique is used to identify errors at boundaries rather than finding those exist in centre of input domain. Boundary value analysis is a next part of Equivalence partitioning for designing test cases where test cases are selected at the edges of the equivalence classes. E.g. if you divided 1 to 1000 input values in valid data equivalence class, then you can select test case values like: 1, 11, 100, 950 etc.