should_not to every object and includes
RSpec::Matchers, a library of standard matchers.
rspec-expectations is currently in alpha release. While you are welcome to track, fork, explore, etc, we're too early in the process to start fielding pull requests and or issues from outside the core development team, so please don't waste your time until this notice changes.
[sudo] gem install rspec --prerelease
This will install rspec, rspec-core, rspec-expectations and rspec-mocks.