Explain Black Box, White Box, and Grey Box Testing

Black Box Testing:

• Definition: Testing without knowledge of internal code structure
• Focus: Functionality and behavior
• Tester Knowledge: No programming knowledge required
• Techniques: Equivalence Partitioning, Boundary Value Analysis, Decision Tables
• Performed By: QA testers, end users
• Examples: Functional testing, UAT, system testing
• Advantages: Unbiased, user perspective, no code access needed
• Disadvantages: Limited coverage, can’t test internal logic

White Box Testing:

• Definition: Testing with full knowledge of internal code structure
• Focus: Internal logic, code paths, algorithms
• Tester Knowledge: Programming knowledge required
• Techniques: Statement Coverage, Branch Coverage, Path Coverage
• Performed By: Developers, technical QA
• Examples: Unit testing, code coverage analysis
• Advantages: Thorough testing, early defect detection, code optimization
• Disadvantages: Time-consuming, requires code access

Grey Box Testing:

• Definition: Combination of black box and white box testing
• Focus: Both functionality and internal structure
• Tester Knowledge: Partial knowledge of internal workings
• Techniques: Matrix testing, regression testing, pattern testing
• Performed By: QA with technical knowledge
• Examples: Integration testing, database testing
• Advantages: Balanced approach, better test coverage
• Disadvantages: Requires both functional and technical skills