Can you explain boundary value analysis?

Answer

In some projects there are scenarios where we need to do boundary value testing. For instance, let's say for a bank application you can withdraw a maximum of 25000 and a minimum of 100. So in boundary value testing we only test the exact boundaries rather than hitting in the middle. That means we only test above the max and below the max. This covers all scenarios. The following figure shows the boundary value testing for the bank application which we just described. TC1 and TC2 are sufficient to test all conditions for the bank. TC3 and TC4 are just duplicate/redundant test cases which really do not add any value to the testing. So by applying proper boundary value fundamentals we can avoid duplicate test cases, which do not add value to the testing.