Status: IN
Some solution files (e.g., `number-of-students-doing-homework-at-a-given-time/solution.py`, `number-of-valid-clock-times/solution.py`) include both the `Solution` class and a `unittest.TestCase` subclass in a single module, alongside a separate `test_solution.py`.
Source: entries/2026/06/06/number-of-students-doing-homework-at-a-given-time-solution.md