Python Pytest Cheat Sheet

Covers writing pytest test functions, fixtures with setup/teardown, parametrized tests, and the most useful command-line options.

1 PageIntermediateMar 28, 2026

Basic Test Functions

pytest discovers functions prefixed with test_.

python

# test_math.pydef add(a, b):    return a + bdef test_add():    assert add(2, 3) == 5def test_add_raises():    import pytest    with pytest.raises(TypeError):        add("2", 3)# Run with: pytest# Run one file: pytest test_math.py# Run one test: pytest test_math.py::test_add# Verbose: pytest -v

Fixtures

Reusable setup/teardown for tests.

python

import pytest@pytest.fixturedef sample_data():    return {"id": 1, "name": "Alice"}def test_name(sample_data):    assert sample_data["name"] == "Alice"@pytest.fixturedef db_connection():    conn = create_connection()    yield conn          # Provided to the test    conn.close()         # Teardown runs after the test@pytest.fixture(scope="session")def api_client():    return APIClient()   # Created once per test session

Parametrized Tests

Run the same test body against many inputs.

python

import pytest@pytest.mark.parametrize("a,b,expected", [    (2, 3, 5),    (0, 0, 0),    (-1, 1, 0),])def test_add_parametrized(a, b, expected):    assert add(a, b) == expected@pytest.mark.parametrize("value", [1, 2, 3])@pytest.mark.parametrize("multiplier", [10, 100])def test_stacked(value, multiplier):    assert value * multiplier > 0   # Stacked marks -> 6 combinations

CLI Options & Markers

Common flags for running and filtering tests.

pytest -k 'add'- Run only tests whose name matches a substring/expression
pytest -m slow- Run only tests marked with @pytest.mark.slow
pytest -x- Stop after the first failing test
pytest --lf- Re-run only the tests that failed last time
pytest -s- Show print() output (disable output capturing)
pytest --cov=myapp- Report test coverage (requires the pytest-cov plugin)
@pytest.mark.skip(reason=...)- Unconditionally skip a test
@pytest.mark.xfail- Mark a test as expected to fail

Pro Tip

Put shared fixtures in a conftest.py file — pytest auto-discovers it without an import, making its fixtures available to every test in that directory and its subdirectories.

Was this cheat sheet helpful?

Python Flask Cheat Sheet

Python AsyncIO Cheat Sheet

Explore Topics

#PythonPytest#PythonPytestCheatSheet#Programming#Intermediate#BasicTestFunctions#Fixtures#ParametrizedTests#CLIOptionsMarkers#Functions#Testing#CheatSheet#SkillVeris

Sri Hayavadhana Info-Tech

Professional Web Designing Services