SmartTest
Python (preview)
SmartTest selects and runs the tests of Python projects that use pytest or unittest. Python is a preview: it never hides a failure, but its precision is coarser than for TypeScript, since the analysis has no types. It reads the sources without running Python.
Supported setups #
| Setup | How SmartTest finds and runs the tests |
|---|---|
pytest (pytest.ini, [tool.pytest.ini_options], [tool:pytest], a conftest.py, or pytest declared as a dependency) | python -m pytest --collect-only -q lists the files; a selection runs with python -m pytest <files>, results read from its JUnit XML |
| unittest (test modules and no pytest setup) | Files named test*.py inside packages, as unittest discover finds them; a selection runs module by module through unittest's own loader |
A Python project is the project root, or any folder with a pyproject.toml, setup.py, setup.cfg, pytest.ini, tox.ini, requirements.txt or conftest.py; smarttest doctor shows pytest (.) collects 12 test file(s).
The interpreter is, in this order: SMARTTEST_PYTHON, python.interpreter in the config, the project's .venv or venv, the active VIRTUAL_ENV, then python3 (python on Windows). A bare command (python3.13) is looked up on PATH; a relative path (.venv/bin/python) is relative to the project.
export default defineConfig({
python: { interpreter: ".venv/bin/python" }, // or { enabled: false } to turn the preview off
});What selects a test #
| You change | Selected |
|---|---|
| A function or a method | The tests that reach it: through from x import f, x.f on an imported module, self.f inside the class |
__init__ (or __new__, __post_init__) | Every test that reaches the class |
Code that runs when the module loads: a statement at module level, a decorator, a class body, a module value built by a call (PATTERN = re.compile(…)) | Every test that imports the module |
A fixture in conftest.py | The tests that ask for it by name (a parameter, @pytest.mark.usefixtures("db")), from the nearest conftest.py that names it |
Code conftest.py runs at load, an autouse fixture, a pytest_* hook | Every test in that folder and below |
| A test module | That test |
pyproject.toml, setup.py, setup.cfg, pytest.ini, tox.ini, requirements*.txt, Pipfile*, poetry.lock, uv.lock, .python-version | Every test in that folder and below |
Imports are resolved from the project root, src/, the pythonpath of the pytest configuration and the folder above a file's top package, as pytest finds them. Relative imports (from ..offer import build), packages (__init__.py) and namespace packages are followed, and so is from package import submodule.
What is uncertainty #
An import SmartTest cannot place is uncertainty: the tests that reach it are selected in BALANCED and SAFE. That covers:
importlib.import_module(name)and__import__(name)with a name built at run time (a literal name is an import);- a module found neither in the project, nor in the standard library, nor among the packages the project declares (
requirements*.txt,pyproject.toml,Pipfile,setup.cfg) or installs in its virtual environment.
Declare the dependencies your code imports, or keep a .venv in the project, and these become ordinary external packages.
Known limits #
- Names reached through dynamic attribute access (
getattr(module, name)) are not seen; neither are monkeypatched functions. smarttest trace(observed execution, which can narrow a selection) records JavaScript only; Python selection is always static.audit --tracesandaudit --mutatecover Python.- A Python project beside a JavaScript one (
service/pyproject.tomlnext to a Vitest app) is analysed by the same run: each side's changes select only its own tests. Its imports resolve from its own folder, aspython -m pytestrun there would.