This is a very simple yet complete example demonstrating how to use Capybara and RSpec to perform integration tests with your Middleman project. These tests can also be modified for plugins so you can use RSpec instead of Cucumber. These examples are all based on the default Middleman page (as created when you type middleman init).
As everyone says, GitHub is about social coding - I didn't just choose to use it because of my love of git as a version control system. I'm not 100% sure this is the best way around this problem - all I know is it works. Feel free chip in & help make this even better.
This example is provided under the terms of the very permissive "Beer-Ware" license:
"THE BEER-WARE LICENSE" (Revision 42):
Simon Rice wrote this. As long as you retain this notice you can do whatever you want with this stuff. If we meet some day, and you think this stuff is worth it, you can buy me a beer in return.
See the LICENSE file or any class or header for the full details.