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Test-layout parity

Rhiza enforces a strict 1:1 parity between source modules and tests, so a test is always easy to locate from the code it covers. The bundled checker (check_test_layout.py) assumes a src/<pkg> source tree and maps src/…/xyz.py to tests/…/test_xyz.py.

Why this repo deviates

This project has no src/ directory. Its "source" is the set of marimo notebooks under book/marimo/notebooks/, and tests/ mirrors those:

Notebook (book/marimo/notebooks/) Mirror test (tests/)
Experiment1.py … Experiment5.py test_experiment1.py … test_experiment5.py
optimize.py test_optimize.py
preamble.py test_preamble.py

Pointed at the default src/, the bundled checker reports every one of these tests as an orphan even though real parity is intact. Two further facts make the stock checker a poor fit here:

  • TitleCased notebooks. The notebooks are Experiment1.py, but their tests are test_experiment1.py; the mapping has to be case-insensitive.
  • A cross-cutting integration test. tests/test_notebook_sharpe.py executes all the experiment notebooks end-to-end and asserts their Sharpe ratios. It has no single source module by design, so it must be allow-listed rather than flagged as an orphan.

The repo-local gate

Rather than disable the check, this repo ships its own layout gate, scripts/check_test_layout.py, that understands the real structure. It verifies that:

  • every notebook module has a mirror tests/test_<name>.py (matched case-insensitively); and
  • every tests/test_*.py maps back to a notebook module, except the declared cross-cutting integration tests (INTEGRATION_TESTS) and the tests that flow down from the rhiza template (TEMPLATE_TESTS, currently tests/test_rhiza_packaging.py).

It is deliberately file-level only: the project exercises its classes (e.g. optimize.Experiment) through plain pytest functions rather than mirrored Test* classes, which is idiomatic pytest.

Run it directly, or let the check-test-layout pre-commit hook run it whenever a notebook or test file changes:

python3 scripts/check_test_layout.py

When you add a notebook, add its mirror test in the same commit. When you add a test that legitimately spans several notebooks, add it to INTEGRATION_TESTS in the gate with a one-line note on what it covers.