Unit Test Generator with Edge Cases

Write comprehensive unit tests for the following function using Vitest. ```TypeScript The function to write tests for ``` Generate tests covering: 1. **Happy path** — Normal, expected inputs and outputs 2. **Edge cases** — Empty inputs, single elements, maximum values, boundary conditions 3. **Invalid inputs** — Wrong types, null/undefined, malformed data 4. **Error scenarios** — What should throw or return error states 5. **Concurrency/timing** — If applicable, race conditions or async edge cases For each test: - Give it a descriptive name that explains what it verifies - Include a brief comment on WHY this case matters - Use arrange-act-assert pattern After the tests, list any additional scenarios that would require integration tests rather than unit tests.