How to run feature specs headlessly or not headlessly at will

by Jason Swett,

I used to prefer seeing my feature specs run in the browser but lately I’ve been preferring to run them headlessly. It’s a little faster that way and I find it a little less disruptive.

Sometimes I still find myself wanting to see a certain test in the browser though. Seeing the test run in the browser can make diagnosis of any problems much easier.

The dream

What would be ideal is if I could do something like the following. To run a spec headlessly, I could do this:

To see the same spec run in the browser, I could do this:

To my surprise and delight, I was able to code something up that turned my dream into reality.

The implementation

Turns out the desired functionality can be implemented by adding just one line to spec/rails_helper.rb:

Now, for any feature spec where js: true is specified, Capybara will use the :selenium_chrome_headless JavaScript driver normally and the :selenium_chrome driver when SHOW_BROWSER=true is specified.

Thanks to Reddit user jrochkind for helping me improve this solution.

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