What is Black box testing and what are its advantages and disadvantages ?

Black box testing is a test design method. It treats the system as a "black-box" so it does not explicitly use the knowledge of the internal structure. In other words, the test engineer does not require to know the internal working of the black box. Black box testing focuses on the functionality part of the module. Black box testing is also known as opaque box and closed box testing. While the term black box testing is more commonly, many people prefer the terms "behavioral" and "structural" for black-box and white-box respectively.
There are bugs that cannot be found using only black box testing or only white box testing. If the test cases are extensive and the test inputs are also from a large sample space then it is always possible to find majority of the bugs through black box testing.

The basic functional or regression testing tools capture the results of black box tests in a script format. Once captured, these scripts can be executed against future builds of an application to verify that new functionality has not disabled previous functionality.

Advantages of Black Box Testing
- It is not important for the tester to be technical. He can be a non-technical person.
- This testing is most likely to find those bugs as the user would have found.
- Testing helps to identify the vagueness and contradiction in functional specifications.
- Test cases can be designed as soon as the functional specifications are complete.

Disadvantages of Black Box Testing
- There are chances of repetition of tests that are already done by the programmer.
- The test inputs needs to be from large sample space.
- It is difficult to identify all possible inputs in limited testing time. So, writing test cases is slow and difficult.
- There are chances of having unidentified paths during testing.

Black Box Testing - Techniques, Advantages, Disadvantages

Black-box testing alludes to tests that are conducted at the software interface. Black-box tests are used to demonstrate that input is properly accepted and output is correctly produced, and that the integrity of external information is maintained. There is no knowledge of the test object's internal structure. This method of test design is applicable to all levels of software testing: unit, integration, functional testing, system and acceptance. Black box testing tends to be applied during later stages of testing.
Main focus in black box testing is on functionality of the system as a whole. The term ‘behavioral testing’ is also used for black box testing.
To implement black box testing strategy, the tester should go through the requirements specifications and a user should know how the system should behave in response to the particular action.
Black-box testing attempts to find errors in the categories like incorrect or missing functions, interface errors, errors in data structures or external database access, behavior or performance errors, and initialization and termination errors.

Advantages of Black Box Testing
- Tester can be non-technical.
- Used to verify contradictions in actual system and the specifications.
- Test cases can be designed as soon as the functional specifications are complete

Disadvantages of Black Box Testing
- The test inputs needs to be from large sample space.
- It is difficult to identify all possible inputs in limited testing time. So writing test cases is slow and difficult.
- Chances of having unidentified paths during this testing.