6.4 Black Box Testing:

Black box testing focuses on the functional requirements of the software. It enables the software engineer to derive sets of input conditions that will fully exercise all functional requirements for program.
Using black box approach, a tester considers the software under test to be an opaque box. There is no Knowledge of its inner structure. The tester only has the knowledge of what it does. The size of the software under test using this approach can vary from a simple module, member function, or subsystem to a complete system.

Several methods of black box approach are:
• Requirement based testing
• Positive and negative testing
• Boundary value analysis
• Equivalence of class partitioning
• State based testing
• Compatibility testing
• User documentation testing
• Domain testing
Requirements testing deals with examining or validating the requirements given in the Software Requirement Specification (SRS) of the system.