Equivalence Partitioning & Boundary-value analysis

Equivalence Partitioning-
A good test case is a test case which has a reasonable probability of finding an error.But as we know,exhaustive input test of program is impossible and that is why we are limited to trying a small subset of all possible inputs.So we want to select the right subset which has highest possibility of finding the most errors. One of the possible way of it is equivalence partitioning.

The equivalence classes are identified by taking each input condition and partitionoing it into two or more groups.
e.g.-for a "X" condition,we can partition it in the valid equivalence class which represents all the valid inputs and invalid equivalence class which represents invalid inputs.


Boundary-Value analysis-
In Boundary value analysis,boundary conditions are on,above & below the edges of input  & output equivalence classes.
Unlike equivalence class,it requires one or more elements to be selected such that each edge of the equivalence class.