```ruby
require 'spec_helper'

describe 'Guard::Interactor::SCOPE' do

  before do
    Guard.stub(:scope=)
    Guard.stub(:setup_interactor)
    Pry.output.stub(puts: true)
    stub_const 'Guard::Bar', Class.new(Guard::Guard)
  end

  let(:guard)     { ::Guard.setup }
  let(:foo_group) { guard.add_group(:foo) }
  let(:bar_guard) { guard.add_guard(:bar, [], [], { :group => :foo }) }

  describe '#perform' do
    context 'without scope' do
      it 'does not call :scope=' do
        Guard.should_not_receive(:scope=)
        Pry.output.should_receive(:puts).with 'Usage: scope <scope>'
        Pry.run_command 'scope'
      end
    end

    context 'with a valid Guard group scope' do
      it 'runs the :scope= action with the given scope' do
        Guard.should_receive(:scope=).with({ :groups => [foo_group], :plugins => [] })
        Pry.run_command 'scope foo'
      end
    end

    context 'with a valid Guard plugin scope' do
      it 'runs the :scope= action with the given scope' do
        Guard.should_receive(:scope=).with({ :plugins => [bar_guard], :groups => [] })
        Pry.run_command 'scope bar'
      end
    end

    context 'with an invalid scope' do
      it 'does not run the action' do
        Guard.should_not_receive(:scope=)
        Pry.run_command 'scope baz'
      end
    end
  end
end
```

Use Ruby 1.8 Hash style
user
```ruby
require 'spec_helper'

describe 'Guard::Interactor::SCOPE' do

  before do
    Guard.stub(:scope=)
    Guard.stub(:setup_interactor)
    Pry.output.stub(:puts => true)
    stub_const 'Guard::Bar', Class.new(Guard::Guard)
  end

  let(:guard)     { ::Guard.setup }
  let(:foo_group) { guard.add_group(:foo) }
  let(:bar_guard) { guard.add_guard(:bar, [], [], { :group => :foo }) }

  describe '#perform' do
    context 'without scope' do
      it 'does not call :scope=' do
        Guard.should_not_receive(:scope=)
        Pry.output.should_receive(:puts).with 'Usage: scope <scope>'
        Pry.run_command 'scope'
      end
    end

    context 'with a valid Guard group scope' do
      it 'runs the :scope= action with the given scope' do
        Guard.should_receive(:scope=).with({ :groups => [foo_group], :plugins => [] })
        Pry.run_command 'scope foo'
      end
    end

    context 'with a valid Guard plugin scope' do
      it 'runs the :scope= action with the given scope' do
        Guard.should_receive(:scope=).with({ :plugins => [bar_guard], :groups => [] })
        Pry.run_command 'scope bar'
      end
    end

    context 'with an invalid scope' do
      it 'does not run the action' do
        Guard.should_not_receive(:scope=)
        Pry.run_command 'scope baz'
      end
    end
  end
end
```
assistant