Marker registration in PyTest - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Purpose of marker registration in pytest

Why is it important to register custom markers in pytest's pytest.ini or pyproject.toml file?

A To avoid warnings about unknown markers during test runs and enable marker-based test selection.

B To automatically generate test reports without additional plugins.

C To speed up test execution by caching marker results.

D To disable all tests that use custom markers by default.

💡 Hint

Think about what happens if pytest sees a marker it does not recognize.

Registering markers tells pytest about custom labels you use on tests. Without registration, pytest shows warnings and may not allow selecting tests by those markers.

❓ Predict Output

intermediate

Output of pytest when using unregistered marker

What output will pytest produce when running this test with an unregistered marker @pytest.mark.slow?

PyTest

import pytest

@pytest.mark.slow
def test_example():
    assert True

A Skips the test silently without any warning.

B Fails the test immediately with a SyntaxError.

C Runs the test without any warning or message.

D Runs the test and shows a warning: 'PytestUnknownMarkWarning: Unknown pytest.mark.slow - is this a typo?'.

💡 Hint

Think about pytest's behavior when it sees a marker it does not know.

Pytest runs the test but warns about unknown markers to alert you to possible typos or missing registrations.

❓ locator

advanced

Correct location to register a custom marker

Where should you add the registration for a custom marker named integration to avoid warnings in pytest?

A In the test function's docstring describing the test purpose.

B Directly inside each test file as a comment above the test function.

C In the <code>pytest.ini</code> file under the <code>[pytest]</code> section with <code>markers = integration: marks tests as integration tests</code>.

D In the <code>setup.py</code> file as an entry point for pytest.

💡 Hint

Think about pytest configuration files that control test behavior globally.

The pytest.ini file is the standard place to register markers so pytest knows about them project-wide.

❓ assertion

advanced

Assertion to verify marker presence on a test function

Given a test function decorated with @pytest.mark.api, which assertion correctly checks for the presence of the 'api' marker in a pytest hook?

PyTest

def pytest_collection_modifyitems(items):
    for item in items:
        # Which assertion is correct here?
        pass

A assert 'api' in item.keywords

B assert any(mark.name == 'api' for mark in item.iter_markers())

C assert item.marker == 'api'

D assert item.has_marker('api')

💡 Hint

Look at how pytest exposes markers on collected test items.

The iter_markers() method returns all markers on a test item. Checking their names is the correct way.

❓ framework

expert

Effect of missing marker registration on test selection

You have registered a custom marker db in pytest.ini. You run pytest -m db to select tests with this marker. What happens if you remove the marker registration but still run pytest -m db?

A Pytest runs only tests with the <code>db</code> marker but shows a warning about unknown marker.

B Pytest runs all tests ignoring the <code>-m db</code> option silently.

C Pytest raises an error and stops because the marker is unknown and cannot be used for selection.

D Pytest skips all tests because no tests match the unregistered marker.

💡 Hint

Consider pytest's behavior when selecting tests by an unregistered marker.

Pytest allows selection by unregistered markers but warns about unknown markers. It runs only matching tests.