You'll need to create and run WebDriver tests in Ruby on OSx using the following components: Ruby version 2.4.1 or higher, an editor such as Vim, Emacs, TextMate, Sublime, or others, a test framework like RSpec, and Mozilla's Gecko Driver proxy for Firefox. To start, install Ruby using Homebrew, then set up a specific working environment with rbenv. Install WebDriver and RSpec, and add the Gecko Driver proxy to your system's PATH environment variable. Write your first test by creating a new file in your chosen editor, requiring the necessary libraries, and defining setup and teardown methods. Run the test by typing `ruby` from the directory where you created the file, which will launch Firefox, navigate to the Sauce Labs home page, and close.