A test suite is a repeatable collection of inputs used to check whether a module still produces correct results after code changes. A Python module can expose this capability through a test mode. section 11.3
A compact file-based regression test typically follows these steps:
- Place representative inputs, including boundary values, in a test file. section 11.3
- Inspect the printed results or save them to a file for checking. section 11.3
- Rerun the same test whenever the module or its functions change. section 11.3
Number-to-words module
A test file contains values such as 0, 21, 999, and 1,000,000,000,000,000. Running `python n2w.py --test < n2w.tst` prints each input with its expected-looking conversion, exposing the unsupported fifteen-digit case.
