Mini Pytest TDD

A tiny exercise to practice TDD with pytest using three features:

• @pytest.mark.parametrize
• pytest.raises
• pytest.approx

You'll implement a few simple math functions working purely with basic float types, then run the tests and iterate until they pass.

What you will implement

Open src/simple_math/core.py and complete these functions (they currently raise NotImplementedError):

• add(a: float, b: float) -> float: Return a + b.
• safe_divide(a: float, b: float) -> float: Return a / b; raise ValueError if b == 0.0.
• average(xs: list[float]) -> float: Return the arithmetic mean; raise ValueError for an empty list.

Each function includes a docstring with examples to guide you.

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Setup & Run (Poetry only)

1. From the project root, install dependencies:

   poetry install

2. Run tests:

   poetry run pytest -q

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TDD Workflow Tips

1. Run tests first to see failures.
2. Implement the smallest change to make one test pass.
3. Re-run tests, refactor only after green.
4. Repeat.

Happy testing! 🎯