安装后rspec没有显示在gem列表中？

Question

安装rspec后，它没有显示在gem列表中。 运行rspec --version后，我收到此消息：

Khalids-MacBook-Pro:~ KNaseem$ rspec --version
/Library/Ruby/Site/2.0.0/rubygems/dependency.rb:308:in `to_specs': Could not find 'rspec-core' (>= 0) among 8 total gem(s) (Gem::MissingSpecError)
Checked in 'GEM_PATH=/Users/khalidnaseem/.rvm/gems/ruby-1.9.3-p194:/Users/khalidnaseem/.rvm/gems/ruby-1.9.3-p194@global', execute `gem env` for more information
    from /Library/Ruby/Site/2.0.0/rubygems/dependency.rb:320:in `to_spec'
    from /Library/Ruby/Site/2.0.0/rubygems/core_ext/kernel_gem.rb:65:in `gem'
    from /usr/local/bin/rspec:22:in `<main>'