Flask Testing Patterns

Untested code is broken code. This skill focuses on production-grade testing workflows.

The Test Client

Use app.test_client() to simulate requests without running a live server.

Fixtures (Pytest)

• app: A fixture that yields a pre-configured application instance.
• db: A fixture that sets up an in-memory database and cleans it after each test.
• client: A pre-authenticated client for integration testing.

Strategic Layers

• Unit Tests: Testing individual models, forms, and business logic.
• Integration Tests: Testing the request/response cycle through views and database persistence.

Best Practices

• Isolated Databases: Always use an in-memory database (e.g., SQLite :memory:) for tests to ensure speed and isolation.
• Coverage: Use pytest-cov to identify untested execution paths.