Mark Decorator

Pytest marking is a feature that enables categorizing tests and applying specific behaviors or actions to them. It involves tagging tests with markers, which can then be utilized to select, filter, or customize how the tests are executed. Pytest provides several built-in markers, such as @pytest.mark.skip to skip a test and @pytest.mark.parametrize to parametrize a test function with multiple input values

Marks are applied to test functions or classes using the @pytest.mark.<MARKER_NAME> decorator.

Expected failure

This marker marks the test as an expected failure.

import pytest

@pytest.mark.xfail
def test_example():
    assert 1 + 1 == 3

Conditionally skipping the test

This marker skips the test if the condition inside evaluated to True.

import sys
import pytest

@pytest.mark.skipif(sys.version_info.major == 3 and sys.version_info.minor < 9,
                    reason="requires Python 3.9 or higher")
def test_something():
    assert True

Skipping the test

This marker skips the test.

import pytest

@pytest.mark.skip(reason="test is not ready yet")
def test_example():
    assert 1 + 1 == 2

Parametrizing the test

We can parametrize a test with multiple sets of input values.

import pytest

@pytest.mark.parametrize("test_input,expected_output", [("3+5", 8), ("2+4", 6), ("6*9", 54)])
def test_eval(test_input, expected_output):
    assert eval(test_input) == expected_output

Mark as a fixture

Using @pytest.mark.usefixtures decorator can be beneficial when we want to reuse a fixture across multipple tests or ensure that a fixture is always used in a particular test.

conftest.py

import pytest

@pytest.fixture
def my_fixture():
    return [1,2,3]

test_file.py

import pytest

@pytest.mark.usefixtures("my_fixture")
def test_with_fixtures():
    assert True