invisibility_spec.rb

module Invisibility
  
  def self.included base
    base.send :attr_reader, :visible
  end
  
  def activate
    @visible = false
  end

  def deactivate
    @visible = true
  end
  
  def visible?
    @visible
  end
end

class Person; end

if $0 =~ /spec/
  describe "invisibility" do
    before do
      Person.send :include, Invisibility
      @bob = Person.new
    end
    subject { @bob }
    
    context 'when given to a Person' do
      it 'creates a #visible? method' do        
        @bob.should respond_to :visible?
      end
    end
    
    context 'activating' do
      specify { should respond_to :activate }
      it '#activate should make the person invisible' do
        subject.activate
        subject.should_not be_visible
      end
    end
    
    context 'deactivating' do
      specify { should respond_to :deactivate }
      it '#deactivate should make a person visible' do
        subject.deactivate
        subject.should be_visible
      end
    end    
  end
end