PY-TEST0012 · owned_test_statement_count

Limit executable statements owned by one collected pytest test.

This is a deterministic rule for python. Read its implementation.

Definition

Count every AST statement owned by each function or method collected through pytest’s default Python conventions. Statements nested under local control flow count because they remain part of the test. A nested function or class counts as one declaration while its body starts an independent scope. Ignore the test docstring and return this test’s statement count. A separate policy can compare the value with a project ceiling such as 25.

Evidence

Evidence records the test range and exact statement count. A default policy can define an explicit maintainability budget rather than claiming that pytest defines a limit. The value is the largest statement count any one collected test owns.

Exceptions

End-to-end tests can configure a larger budget when one behavior genuinely needs a long scenario. Prefer fixtures for reusable setup and parametrization for repeated cases. Do not extract a single-use helper merely to satisfy the number because that hides the test’s algorithm without reducing it.

Examples

Bad

def test_checkout(client):
    # More than 25 separate setup, action, and assertion statements.
    ...

Good

def test_checkout(configured_cart, client):
    response = client.post("/checkout", json=configured_cart)
    assert response.status_code == 201
    assert response.json()["state"] == "paid"

References

• Cites “pytest documentation”, anatomy of a test. Open reference
• Cites “pytest documentation”, fixtures. Open reference
• Cites “pytest documentation”, parametrization. Open reference