What is the purpose of unit testing and provide a boundary value test for a function that accepts inputs in the range 0 to 100?

• A. Unit tests verify integration with databases; boundary test checks 50 and 60.
• B. Unit tests ensure performance; boundary test checks max latency.
• C. Unit tests verify individual components; boundary values: 0, 1, 99, 100, and just outside: -1, 101.
• D. Unit tests focus on UI; boundary test checks color values.

Answer: (C)

Unit testing aims to verify that individual components of code work correctly in isolation. For a function that accepts inputs in the range 0 to 100, boundary value testing focuses on the edges of that range and values just beyond. Test 0 and 100 to hit the boundaries, and 1 and 99 to check behavior just inside those edges. Also include values just outside like -1 and 101 to confirm how invalid inputs are handled. This approach helps catch off-by-one mistakes and ensures consistent handling at the limits, whether the function clamps, throws an error, or returns a special value. In contrast, testing choices that focus on integration with databases, performance, or UI miss the point of unit testing and boundary value analysis for input ranges.