Which testing approach verifies internal code paths and logic?

• A. Black-Box Testing Verifies External Behavior
• B. Grey-Box Testing Validates External Behavior With Some Knowledge Of Code
• C. Unit Testing Tests Individual Components In Isolation
• D. White-Box Testing Verifies Internal Code Paths And Logic

Answer: (D)

White-box testing uses knowledge of the program’s internal structure to verify internal code paths and logic. By examining the code, testers design tests that exercise specific branches, conditions, and paths, ensuring each path behaves as intended and catching issues like untested branches, dead code, or incorrect decisions that external-behavior tests might miss. This approach directly targets how the code executes, not just what it does from the outside. In contrast, black-box testing focuses on external behavior without looking at internal structure, grey-box testing uses partial internal knowledge, and unit testing, while often white-box in practice, centers on individual components rather than the full scope of internal path verification.