# DEMO — reproducible small bug fix

Self-created demonstration only; not client work and not evidence of commercial history. `broken_demo.py` intentionally subtracts percentage points instead of computing a percentage discount. `fixed_demo.py` corrects that single behavior and includes input bounds. The regression test is intentionally written against the corrected behavior.

Run the fixed tests with Python 3:

```text
python -m unittest -v test_demo.py
```

Expected result: 3 tests pass. The original example produces 240 for a 250 subtotal at 10%, while the test expects 225.