Black Box Testing, Its Advantages and Disadvantages

Black Box Testing is a testing technique where no knowledge of the internal functionality and structure of the system is available. This testing technique treats the system as a black box or closed box. The tester only knows the formal inputs and expected outputs, but does not know how the program actually arrives at those outputs. As a result, all testing must be based on functional specifications. For this reason black box testing is also considered to be functional testing and is also a form of behavioral testing or opaque box testing or simply closed box testing. Although black box testing is behavioral testing, behavioral test design is slightly different from black box test design because internal knowledge may be available in behavioral testing.

Advantages of Black Box Testing

• Efficient when used on large systems.
• SInce the tester and developer are independent of each other, testing is balanced and unprejudiced.
• Tester can be non-technical.
• There is no need for the tester to have detailed functional knowledge of system.
• Tests will be done from an end user's point of view, because the end user should accept the system. (This testing technique is sometimes also called Acceptance testing.)
• Testing helps to identify vagueness and contradictions in functional specifications.
• Test cases can be designed as soon as the functional specifications are complete.

Disadvantages of Black Box Testing

• Test cases are challenging to design without having clear functional specifications.
• It is difficult to identify tricky inputs if the test cases are not developed based on specifications.
• It is difficult to identify all possible inputs in limited testing time. As a result, writing test cases may be slow and difficult.
• There are chances of having unidentified paths during the testing process.
• There is a high probability of repeating tests already performed by the programmer.