pytest.mark Decorators

pytest.mark Decorators

Markers let you categorize, filter, and control test execution. pytest comes with several built-in markers, and you can create your own.

Common Built-in Markers

import pytest

@pytest.mark.slow
def test_heavy_computation():
    result = expensive_calculation()
    assert result is not None

@pytest.mark.skip(reason="Not implemented yet")
def test_future_feature():
    pass

@pytest.mark.xfail(reason="Known bug #123")
def test_known_failure():
    assert False

@pytest.mark.parametrize("input,expected", [
    (1, 2),
    (2, 4),
    (3, 6),
])
def test_double(input, expected):
    assert input * 2 == expected

Running Tests by Marker

Use the -m flag to run only tests with a specific marker:

# Run only slow tests
pytest -m slow

# Run tests that are NOT slow
pytest -m "not slow"

# Combine markers
pytest -m "slow or performance"

Registering Custom Markers

To avoid warnings, register your custom markers in pytest.ini:

[pytest]
markers =
    slow: marks tests as slow
    smoke: marks tests as quick smoke tests
    integration: marks tests requiring external services

Marker with Parameters

You can pass keyword arguments to markers:

@pytest.mark.timeout(10)
def test_quick():
    pass

@pytest.mark.skipif(
    sys.platform == "win32",
    reason="Does not work on Windows"
)
def test_unix_only():
    pass