git clone https://github.com/rspec/rspec-core.git
cd rspec-core
gem install bundler
bundle install
Now you should be able to run any of:
rake
rake spec
rake cucumber
Or, if you prefer to use the rspec and cucumber commands directly, you can either:
bundle exec rspec
Or ...
bundle install --binstubs
bin/rspec
The Gemfile includes the gems you'll need to be able to run specs. If you want to customize your dev environment with additional tools like guard or ruby-debug, add any additional gem declarations to Gemfile-custom (see Gemfile-custom.sample for some examples).