One of my colleagues once described the Ruby community as "Test Infected" and if any library epitomizes this it's Capybara, which has gained popularity exponentially since it was first released. The Ruby community certainly owes its creator Jonas Nicklas a great deal of thanks for bringing peace and harmony to many test automation code bases around the globe.
The proof of Capybara's success is the way in which its use has spread far beyond just testing Rails applications and now supports testing of many web applications written in a wide variety of languages and frameworks. Capybara's functionality has also been replicated in languages other than Ruby again highlighting just how powerful the concept is.
So what is Capybara?
Capybara provides a domain-specific language for test automation; this DSL extends the human-readable BDD style of frameworks such as Cucumber and RSpec into the automation code itself. For example, opening a browser and navigating to a URL is as simple as visit http://google.com. This is a vast improvement over typical test APIs.
Additionally Capybara allows us to write tests once and run them in any compatible driver. The driver ecosystem is vibrant and switching libraries is as simple as adding an additional gem and making a one-line change to your code.
Capybara is quite literally your one-stop shop for test automation.