pytest-fixtures

Pytest fixtures are reusable functions that prepare test data and state. Define them in a conftest.py file or in your test module using the @pytest.fixture decorator, then pass the fixture name as a parameter to your test functions. Fixtures automatically inject their return value into tests, eliminating duplicate setup code.

Fixture scope controls how long a fixture's state persists. Function scope (default) creates a fresh instance for each test; module scope reuses it across all tests in one file; session scope maintains it across your entire test run. Choose based on whether you need isolation or efficiency for expensive setup operations.

The @pytest.mark.parametrize decorator lets you specify multiple input sets for a single test function. List parameter names and values, and pytest runs your test once for each combination. This eliminates repetitive test functions and ensures consistent coverage of edge cases.

Yes. Create a conftest.py file at your project root or in any subdirectory, define fixtures there, and pytest automatically discovers and makes them available to all test files in that directory and below. This centralizes fixture logic and eliminates duplication across your test suite.

Pytest fixtures can request other fixtures as parameters, creating a dependency chain. Pytest resolves the chain automatically, running dependencies first and passing their return values down. This enables composable, layered setup without manual sequencing.

Use yield in a fixture to run cleanup code after each test. Code before yield is setup; code after yield is teardown. This ensures resources like database connections, temp files, or mocks are properly released, preventing test pollution and resource leaks.