Black Box and White BoxTesting

Black box testing is a Software testing technique to test the functionality of software without having knowledge on internal working structure of the code. This kind of testing is done based on requirements of application. For black box testing it is not mandatory to know internal working structure of software and it is enough to have a functional knowledge of the software.

For example:

Login Screen with user name and password input field.

1) Provide valid input for user name and password and verify we can able to login successfully.

2) Provide invalid input for user name and valid password and verify we should not able to login.

In this case we don't know the internal working structure of code, just tester should know knowledge on valid input to login successfully and invalid input for unsuccessful authenticate.

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White Box testing done based on analysis of internal working structure of software/program. It is also known as structure/clear/glass box testing. White box testing is performed based on the knowledge of how the system is implemented. Mostly developer may do this testing, because they are well known on the internal working structure of the program such as statement coverage, branch coverage and path coverage.