What is black box testing & White box testing?

The Black box testing is also termed as functional testing. It ignores how the internal functionality of a system works & depends only what are the outputs on specified inputs. The Source code availability is not important in back box testing. The Black box testing is mostly to ensure that it meets the user functionality.

According to the IEEE standards following are the characteristics of Black box testing:-

1) "The Testing which ignores the internal mechanism of the system or component & focuses solely on the outputs generated in response to selected inputs and execution conditions;"

2) "The Testing conducted to evaluate the compliance of a system or component with the specified functional requirements."

The One way of black box testing is the Manual testing what the tester performs. For illustrate you can install the application on a machine and tester starts testing is a type of black box testing. In this case the tester is completely unaware of how the program logic flows and how it is coded etc.

The White box testing is opposite to the Black box it requires internal know how of how the logic flows. As this testing requires know how of the internal structure it can only be done programmers. The Unit testing is one of the ways of doing White box testing in which the programmers use NUNIT or JNUIT to test each class individually. The White box testing can be completed by programmer by either stepping through the code or by testing the classes and components in isolation.