Black Box vs White Box Testing

Black Box Testing
Black box testing refers to testing of the application without taking into account the internal structure of the program. As long as the program returns correct results based on the input parameters, the testing is considered to be valid.

Advantages:-
1. It mimics end user behavior.
2. It can uncover missing specifications.
3. It allows to test portions of the applications that are not currently implemented
4. As tester is independent of developer, it allows for uncompromised testing
5. Tester need not have knowledge about the internal structure of the program
6. For large systems, it simplifies the testing by ensuring all the inputs and outputs are tested

Disadvantages:-
1. All possible scenarios may not be covered
2. It does not allows for structural testing of the system
3. Test cases need to be redesigned with change in input methods or user interface
Common Black Box testing methodologies:-
1. Decision table testing
2. Pair wise testing
3. State transition tables
4. Use case testing
5. Cross-functional testing


White Box testing
White box testing refers to testing of the application taking into account the internal structure of the program. It is also referred to as structural, glass box or transparent box testing. It requires understanding of the coding language and underlying architecture of the program.

Advantages:-
1. It ensures that all possible execution paths are traversed at least once.
2. It offers greater stability and reusability if the basic components of the application does not change
3. It ensures complete testing of all possible input and output parameters

Disadvantages:-
1. It does not mimics end user behavior
2. The tester needs to know the workings of the code and language used in application design.
3. Test cases are complex and difficult to execute than black box testing

Common white box testing methodologies:-
1. Control flow testing
2. Data flow testing
3. Branch testing
4. Path testing