Fixture scope with parallel tests in PyTest - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the fixture scope 'function' mean in pytest?

The fixture is created and destroyed for each test function. It ensures a fresh setup for every test.

intermediate

How does the 'session' scope affect fixture usage in parallel tests?

The fixture is created once per test session and shared across all tests, which can cause conflicts if tests run in parallel and modify shared state.

beginner

Why is 'function' scope recommended for fixtures when running tests in parallel?

Because each test gets its own fixture instance, avoiding shared state and race conditions between parallel tests.

intermediate

What problem can arise if a 'module' scoped fixture is used with parallel tests?

Tests running in parallel might share the same fixture instance, leading to unpredictable behavior or test failures due to shared mutable state.

advanced

How can you safely share resources in pytest fixtures when running tests in parallel?

Use locks or external services designed for concurrency, or limit fixture scope to 'function' to avoid sharing mutable state.

Which fixture scope creates a new fixture instance for each test function?

A session

B function

C module

D package

The 'function' scope means the fixture is created fresh for each test function.

What is a risk of using 'session' scoped fixtures with parallel tests?

A Tests run slower

B Tests cannot access the fixture

C Fixtures are recreated too often

D Shared state can cause conflicts

Session scoped fixtures are shared across tests, so parallel tests might conflict if they modify shared state.

To avoid race conditions in parallel tests, which fixture scope is safest?

A function

B session

C module

D class

Function scope ensures each test has its own fixture instance, preventing shared state issues.

If you want to share a database connection safely in parallel tests, what should you do?

A Use a module scoped fixture and ignore conflicts

B Use a session scoped fixture without locks

C Use a function scoped fixture or add synchronization

D Avoid fixtures and create connections manually

Either create fresh connections per test or use synchronization to avoid conflicts.

What pytest plugin helps run tests in parallel?

A pytest-xdist

B pytest-mock

C pytest-cov

D pytest-html

pytest-xdist allows parallel test execution.

Explain how fixture scope affects test isolation when running tests in parallel.

Think about how sharing or isolating resources impacts test reliability.

Describe strategies to safely share resources in pytest fixtures during parallel test execution.

Consider how to prevent race conditions and conflicts.