How to run a single RSpec test?

I have the following file:

/spec/controllers/groups_controller_spec.rb

What command in terminal do I use to run just that spec and in what directory do I run the command?

My gem file:

# Test ENVIRONMENT GEMS
group :development, :test do
    gem "autotest"
    gem "rspec-rails", "~> 2.4"
    gem "cucumber-rails", ">=0.3.2"
    gem "webrat", ">=0.7.2"
    gem 'factory_girl_rails'
    gem 'email_spec'
end

Spec file:

require 'spec_helper'

describe GroupsController do
  include Devise::TestHelpers

  describe "GET yourgroups" do
    it "should be successful and return 3 items" do

      Rails.logger.info 'HAIL MARRY'

      get :yourgroups, :format => :json
      response.should be_success
      body = JSON.parse(response.body)
      body.should have(3).items # @user1 has 3 permissions to 3 groups
    end
  end
end

Not sure how long this has bee available but there is an Rspec configuration for run filtering - so now you can add this to your spec_helper.rb:

RSpec.configure do |config|
  config.filter_run_when_matching :focus
end

And then add a focus tag to the it, context or describe to run only that block:

it 'runs a test', :focus do
  ...test code
end

RSpec documentation:

https://www.rubydoc.info/github/rspec/rspec-core/RSpec/Core/Configuration#filter_run_when_matching-instance_method