rspecとrspec-mocksをインストールしたばかりですが、最も簡単なセットアップを実行できません
irb(main):001:0> require 'rspec'
=> true
irb(main):004:0> require 'rspec/mocks'
=> false
irb(main):006:0> RSpec::Mocks::setup(Object.new)
NameError: uninitialized constant BasicObject::RSpec
from /usr/local/Cellar/ruby/1.9.1-p376/lib/ruby/gems/1.9.1/gems/rspec-mocks-2.13.0/lib/rspec/mocks.rb:60:in `block in add_extensions'
from /usr/local/Cellar/ruby/1.9.1-p376/lib/ruby/gems/1.9.1/gems/rspec-mocks-2.13.0/lib/rspec/mocks.rb:60:in `class_eval'
from /usr/local/Cellar/ruby/1.9.1-p376/lib/ruby/gems/1.9.1/gems/rspec-mocks-2.13.0/lib/rspec/mocks.rb:60:in `add_extensions'
from /usr/local/Cellar/ruby/1.9.1-p376/lib/ruby/gems/1.9.1/gems/rspec-mocks-2.13.0/lib/rspec/mocks.rb:11:in `setup'
from (irb):6
from /usr/local/Cellar/ruby/1.9.1-p376/bin/irb:12:in `<main>'
何が間違っているのだろうか、他の宝石をロードする必要がありますか?