This one took a while and required extensive help from a rocket scientist. While running RSpec I got this.
.../test/ruby/1.9.1/bundler/gems/rspec-expectations-68f857b9b668/lib/rspec/expectations/extensions/kernel.rb:27: in `should': uninitialized constant RSpec::Expectations::PositiveExpectationHandler (NameError)
The problem was that you need to configure the expectations framework in spec\spec_helper.rb. The expect_with :rspec is the fix.
You can read more about rspec configuration here.