Pytest Interview Questions and Answers

Answer: Extension points for customizing pytest behavior

Hooks are functions pytest calls at specific points. Define in conftest.py or plugins. Examples: pytest_configure, pytest_collection_modifyitems. Powerful customization.

Answer: Python testing framework with simple syntax

Pytest is a mature, feature-rich Python testing framework. It provides simple syntax with powerful features like fixtures, parametrization, and plugins.

Answer: Runs test with multiple input sets

@pytest.mark.parametrize runs test with different inputs. Creates separate test per input set. Clear reporting per case. Essential for data-driven testing.

Answer: @pytest.mark.parametrize('args', [values])

@pytest.mark.parametrize("x,y,expected", [(1,2,3), (2,3,5)]). First arg is parameter names, second is value tuples. Multiple parameters comma-separated.

Answer: pip install pytest

Install Pytest with pip install pytest. Use pip install -U pytest to upgrade. Check version with pytest --version. Also available via conda.

Answer: Hook to modify collected test items

pytest_collection_modifyitems(config, items) modifies collected tests. Reorder, filter, mark tests. Runs after collection. Useful for dynamic test configuration.

Answer: test_*.py or *_test.py

Test files must start with test_ or end with _test.py. Examples: test_example.py, example_test.py. Pytest auto-discovers these files.

Answer: Hook called after config is initialized

pytest_configure(config) runs after config initialized. Register plugins, markers. Access config. Early customization point. Runs once per session.

Answer: function, class, module, package, session

Fixture scopes: function (default), class, module, package, session. Determines when fixture is setup/torn down. Broader scope = shared across more tests.

Answer: Hook called before test execution

pytest_runtest_setup(item) runs before each test. Modify test environment. Runs before fixtures. Access test item metadata. Per-test customization.

Answer: Must start with test_

Test functions must start with test_. Example: def test_addition(). Test classes must start with Test (no __init__). Pytest auto-discovers these.

Answer: Automatically applies fixture to all tests

@pytest.fixture(autouse=True) applies automatically to all tests in scope. No need to request explicitly. Useful for setup/teardown that always applies.

Answer: Create module with hooks and register

Create module with pytest hooks. Register: pytest_plugins = ["mymodule"] in conftest.py or setup.py entry_points. Distribute via pip. Reusable customizations.

Answer: Separates setup from teardown code

yield in fixtures separates setup (before yield) from teardown (after yield). @pytest.fixture def resource(): setup(); yield value; teardown(). Cleaner than return.

Answer: Both a and b

Run tests with pytest or python -m pytest. Both work. Pytest discovers and runs all test files in current directory and subdirectories.

Answer: Fixtures can depend on other fixtures

Fixtures can depend on other fixtures by requesting them as parameters. Creates dependency graph. Pytest manages order automatically. Enables composition.

Answer: pytest test_file.py

Run specific file: pytest test_file.py. Can specify multiple files. Use path/to/test_file.py for files in subdirectories.

Answer: Hook to add custom command-line options

pytest_addoption(parser) adds CLI options. parser.addoption("--myopt"). Access with config.getoption("myopt"). Define custom test behavior via CLI.

Answer: pytest test_file.py::test_function

Run specific test: pytest test_file.py::test_function. Use :: separator. Can also specify class: pytest test_file.py::TestClass::test_method.

Answer: Hook for custom parametrization logic

pytest_generate_tests(metafunc) enables custom parametrization. metafunc.parametrize(). More flexible than @pytest.mark.parametrize. Dynamic test generation.

Answer: Metadata tags for tests

Markers are metadata tags: @pytest.mark.slow, @pytest.mark.integration. Filter tests: pytest -m slow. Register in pytest.ini. Custom markers supported.

Answer: Pytest can run doctests with --doctest-modules

pytest --doctest-modules runs doctests. --doctest-glob="*.rst" for rst files. Integrates doctests into test suite. Useful for documentation testing.

Answer: Register in pytest.ini or pyproject.toml

Register markers in pytest.ini: [pytest] markers = slow: marks slow tests. Or pyproject.toml. Use @pytest.mark.slow. Run with pytest -m slow.

Answer: Python assert statement for test verification

Pytest uses Python's assert statement. assert expression shows detailed failure info. Pytest rewrites assert for better error messages. Simple and powerful.