Fixture scope (function, class, module, session) in PyTest - Framework Patterns

Framework Mode - Fixture scope (function, class, module, session)

Folder Structure

project-root/
├── tests/
│   ├── test_example.py
│   ├── test_another.py
│   ├── conftest.py
│   └── submodule/
│       └── test_submodule.py
└── pytest.ini
  

Test Framework Layers

• Fixtures Layer: Defined in conftest.py or test modules, fixtures provide setup and teardown code with different scopes: function, class, module, and session.
• Test Layer: Test files inside tests/ folder use fixtures to run tests. Each test function or method can request fixtures.
• Configuration Layer: pytest.ini or pyproject.toml files configure pytest options and plugins.
• Utilities Layer: Helper functions or classes can be placed in separate modules imported by fixtures or tests.

Configuration Patterns

Use conftest.py files to define fixtures with appropriate scopes:

• function: Runs before each test function. Use for isolated setup.
• class: Runs once per test class. Use when tests share setup in a class.
• module: Runs once per test module (file). Use for expensive setup shared by all tests in a file.
• session: Runs once per test session. Use for global setup like database connections.

Example fixture with scope:

import pytest

@pytest.fixture(scope="module")
def setup_database():
    print("Setup DB")
    yield
    print("Teardown DB")
  

Use pytest.ini to configure test runs, e.g., markers or test paths.

Test Reporting and CI/CD Integration

• Use pytest plugins like pytest-html or pytest-cov to generate reports.
• Configure CI/CD pipelines (GitHub Actions, Jenkins, GitLab CI) to run pytest commands and collect reports.
• Fixture scopes help optimize test run time by reducing repeated setup, improving CI efficiency.

Best Practices

• Use the narrowest fixture scope needed to keep tests isolated and fast.
• Use function scope for tests that must not share state.
• Use session scope for expensive global setup to speed up test runs.
• Keep fixtures simple and focused on setup/teardown only.
• Use conftest.py to share fixtures across multiple test files.

Self Check

Where in this framework structure would you add a new fixture that sets up a web browser once per test class?

Key Result

Use pytest fixtures with appropriate scopes (function, class, module, session) to organize setup and teardown efficiently.