Lewis Buckley

August 9, 2023

Faster Rails system tests

Here's a tip for speeding up your Rails system test suite.

You may well have a test helper to authenticate a user before continuing with your actual test. Something like this is typical:


Instead of authenticating in every system test like this, it's possible to directly set a session cookie, saving a few steps in the process. Here's how we did it with Capybara, Selenium and ChromeDriver (gist):


Andrey Novikov shared a gist showing a similar technique for Rspec and Devise: https://gist.github.com/Envek/9981207c79579db081897abd1afb80db

The tradeoff is that this method makes system tests less realistic. You'll want to ensure you have good independent coverage of your authentication mechanism.

We saw a 25% reduction in overall test suite run time after we updated HEY system tests to use this method. Let me know what improvement you see!

About Lewis Buckley

Programmer at 37signals, living in Devon 🇬🇧