Why markers categorize and control tests in PyTest - Test Execution Impact

Test Overview

This test demonstrates how pytest markers categorize tests and control which tests run. It verifies that only tests with a specific marker run when selected.

Test Code - pytest

PyTest

import pytest

@pytest.mark.slow
def test_slow_feature():
    assert 2 + 2 == 4

@pytest.mark.fast
def test_fast_feature():
    assert 1 + 1 == 2

# Run command: pytest -m slow

Execution Trace - 5 Steps

Step	Action	System State	Assertion	Result
1	Test runner starts and reads test file	Test file with two tests: one marked 'slow', one marked 'fast'	-	PASS
2	Pytest filters tests to run only those marked 'slow' using '-m slow'	Only test_slow_feature is selected to run	-	PASS
3	Pytest runs test_slow_feature	Executing test_slow_feature function	Assert 2 + 2 == 4	PASS
4	Pytest deselects test_fast_feature because it is not marked 'slow'	test_fast_feature is deselected	-	PASS
5	Test run completes with only 'slow' tests executed	Test report shows 1 passed, 1 deselected, 0 skipped	Verify only tests with 'slow' marker ran	PASS

Failure Scenario

Failing Condition: Marker name is misspelled or test run command uses wrong marker

Execution Trace Quiz - 3 Questions

What does the '-m slow' option do in pytest?

A Runs tests in alphabetical order

B Runs all tests except those marked 'slow'

C Runs only tests marked with 'slow'

D Skips all tests

Key Result

Using markers in pytest helps organize tests into groups so you can run only relevant tests, saving time and focusing on specific features.