Behaviour Driven Development for Ruby

# RSpec Expectations

rspec-expectations adds `should` and `should_not` to every object and includes
RSpec::Matchers, a library of standard matchers.

## Documentation

* [Cucumber features](http://relishapp.com/rspec/rspec-expectations)
* [RDoc](http://rubydoc.info/gems/rspec-expectations/2.4.0/frames)