Running tests by marker (-m) in PyTest - Build an Automation Script

Run pytest tests filtered by marker

Preconditions (2)

Step 1: Open terminal or command prompt

Step 2: Navigate to the directory containing the test file

Step 3: Run pytest with the -m option to specify the marker 'smoke'

Step 4: Observe that only tests marked with @pytest.mark.smoke are executed

✅ Expected Result: Only tests with the 'smoke' marker run and pass or fail accordingly

Automation Requirements - pytest

Assertions Needed:

Verify that only tests with the specified marker run

Verify that tests without the marker do not run

Best Practices:

Use @pytest.mark.<marker_name> to mark tests

Use pytest command line option -m '<marker_name>' to filter tests

Keep test markers meaningful and documented

Automated Solution

PyTest

import pytest

@pytest.mark.smoke
 def test_smoke_1():
     assert 1 + 1 == 2

@pytest.mark.smoke
 def test_smoke_2():
     assert 'a' * 3 == 'aaa'

@pytest.mark.regression
 def test_regression_1():
     assert 5 > 2

@pytest.mark.regression
 def test_regression_2():
     assert len([1, 2, 3]) == 3

# To run only smoke tests, execute in terminal:
# pytest -m smoke

# Expected output: only test_smoke_1 and test_smoke_2 run

The code defines four test functions with two different markers: smoke and regression.

Using @pytest.mark.smoke marks tests as smoke tests, and @pytest.mark.regression marks others as regression tests.

Running pytest -m smoke in the terminal runs only the tests marked with smoke. This filters tests by marker, so tests without the marker are skipped.

This approach helps run specific groups of tests quickly, like smoke tests for basic checks.

Common Mistakes - 3 Pitfalls

{'mistake': 'Not marking tests with @pytest.mark before running with -m', 'why_bad': "The -m option filters by markers, so if tests are not marked, they won't be selected.", 'correct_approach': 'Always decorate tests with @pytest.mark.<marker_name> before using -m to filter.'}

Using incorrect marker name in the -m option

Hardcoding test names instead of using markers for filtering

Bonus Challenge

Add a new marker 'fast' and create two tests with it. Run tests filtered by 'fast' marker.

Show Hint