Write Unit Tests

Generate a comprehensive unit test suite for the following function. Function code: [paste your function here] Language/framework: [e.g., Python/pytest, JavaScript/Jest, Go/testing] Please: 1. Write tests for the happy path (expected inputs and outputs) 2. Write tests for all edge cases (empty input, null, boundary values, large input) 3. Write tests for expected error/exception cases 4. Use descriptive test names that explain what is being tested 5. Add a brief comment above each test group explaining the scenario 6. Follow AAA structure (Arrange, Act, Assert) 7. Achieve at least 90% branch coverage Output: A complete, runnable test file I can copy directly into my project.