What is black box testing and how is it conducted?

Black box testing is a software testing technique that focuses on the external behavior of the software without considering its internal structure or implementation details. It is performed to evaluate the functionality and usability of the software from an end-user's perspective.

During black box testing, the tester does not have any knowledge of the internal code or logic of the software being tested. The tester treats the software as a black box, where inputs are provided, and the corresponding outputs are observed and analyzed. The goal is to identify any discrepancies between the expected behavior and the actual behavior of the software.

Black box testing is conducted by following these steps:

1. Requirement Analysis: The tester thoroughly understands the software requirements and specifications to determine the expected behavior.

2. Test Case Design: Based on the requirements, the tester designs test cases that cover different scenarios and functionalities of the software. These test cases include input values, expected outputs, and any preconditions or postconditions.

3. Test Execution: The designed test cases are executed on the software without any knowledge of its internal workings. The tester provides inputs to the software and observes the outputs, comparing them with the expected results.

4. Defect Reporting: If any discrepancies or failures are found during the test execution, the tester reports them as defects or bugs. These issues are then documented and communicated to the development team for further investigation and resolution.

5. Regression Testing: After the defects are fixed, regression testing is performed to ensure that the changes or fixes do not introduce new issues or impact the existing functionality.

6. Test Closure: Once all the test cases are executed, and the software meets the expected behavior, the black box testing phase is concluded, and a test closure report is prepared.

Black box testing techniques include equivalence partitioning, boundary value analysis, decision table testing, state transition testing, and error guessing. These techniques help in designing effective test cases that cover a wide range of scenarios and increase the chances of finding defects in the software.