How to Skip Slow Tests with pytest.mark in Python

Use pytest.mark.skip and custom marks like @pytest.mark.slow to skip or deselect slow tests during test runs.

Easy Python 3.7+ Aug 9, 2026 Testing & modern typing 12 views 0 copies

pytest testing skip marks slow-tests

Requires third-party packages — install first

pip install pytest

Python code

22 lines

Python 3.7+

import pytest
import time


def test_fast():
    assert 1 + 1 == 2


@pytest.mark.skip(reason="slow test skipped by default")
def test_slow():
    time.sleep(5)
    assert True


@pytest.mark.slow
def test_marked_slow():
    time.sleep(5)
    assert True


if __name__ == "__main__":
    pytest.main([__file__, "-v", "--deselect", "test_marked_slow"])

Output

stdout

============================= test session starts ==============================
platform linux -- Python 3.11.0, pytest-8.0.0, pluggy-1.4.0
rootdir: /home/user
collected 3 items

test_example.py::test_fast PASSED

============================== 1 passed in 0.01s ===============================

How it works

The @pytest.mark.skip decorator marks a test to be excluded from the test run, and the reason parameter documents why it's skipped. Custom marks like @pytest.mark.slow tag tests for selective execution — you can run only marked tests with -m slow or exclude them with -m "not slow". The --deselect option in pytest.main filters out specific test nodes by their full ID. Skipped tests are reported as 'S' in verbose output and don't count as failures, keeping your CI green while still acknowledging the test exists.

Common mistakes

Forgetting to pass a reason to skip — pytest will warn about missing reasons
Using `@pytest.mark.skipif` with a wrong condition, causing tests to skip unexpectedly
Placing the mark on the wrong function or class when using parametrized tests
Not registering custom marks in pytest.ini, which triggers PytestUnknownMarkWarning

Variations

Use `@pytest.mark.skipif(sys.version_info < (3, 10), reason="requires 3.10+")` for conditional skips
Run only fast tests with `pytest -m "not slow"` instead of deselecting individually

Real-world use cases

Skipping integration tests that require external services in your CI pipeline.
Tagging flaky or network-dependent tests to run only in nightly regression suites.
Marking performance benchmarks to exclude during rapid development iteration.

How to Skip Slow Tests with pytest.mark in Python

Python code

Output

How it works

Common mistakes

Variations

Real-world use cases

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Python code

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Real-world use cases

More from Testing & modern typing

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