Running with -n auto in PyTest - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the pytest option -n auto do?

It runs tests in parallel using all available CPU cores automatically, speeding up test execution.

beginner

Why is running tests with -n auto useful?

Because it uses all CPU cores to run tests at the same time, reducing total test time like having many cooks in the kitchen.

beginner

What must be installed to use -n auto in pytest?

You need the pytest-xdist plugin installed to enable parallel test execution.

intermediate

How does pytest decide how many workers to use with -n auto?

It automatically detects the number of CPU cores on your machine and uses that number of workers.

intermediate

What is a potential issue when running tests with -n auto?

Tests that share state or resources might fail or interfere with each other if not designed for parallel runs.

What plugin is required to run pytest with -n auto?

A pytest-cov

B pytest-xdist

C pytest-mock

D pytest-html

The pytest-xdist plugin enables parallel test execution with -n option.

What does -n auto do in pytest?

A Runs tests in parallel using all CPU cores

B Runs tests sequentially

C Runs tests only on one CPU core

D Runs tests with verbose output

-n auto runs tests in parallel using all available CPU cores automatically.

If you run pytest with -n auto, how many workers will it use?

A Number of CPU cores

B Two workers

C Number of tests

D One worker

pytest detects your CPU cores and uses that many workers for parallel testing.

What is a risk of running tests with -n auto?

A Tests run slower

B Tests will not run at all

C Tests lose coverage data

D Tests may interfere if they share resources

Tests sharing state or files might conflict when run in parallel.

How can you install the plugin needed for -n auto?

A pip install pytest-auto

B pip install pytest-parallel

C pip install pytest-xdist

D pip install pytest-runner

Use pip install pytest-xdist to add parallel test support.

Explain how pytest's -n auto option improves test execution.

Think about how multiple cooks can prepare food faster than one.

Describe a scenario where running tests with -n auto might cause problems.

Imagine two people trying to write on the same paper at once.