command_factory_spec.rb

#command_factory_spec.rb:

require 'spec_helper'

describe CommandFactory do

  let(:factory) { CommandFactory.new nil }
  subject { factory.command(:foo) }
  
  context 'a thing' do
  
    it_behaves_like "a command"

  end
end

# shared_examples_for_commands.rb:
    
shared_examples "a command" do

  # your way (fixed)
  #it "should respond to execute" do
  #  subject.should respond_to(:execute)
  #end
  #better way
  it { should respond_to :execute }

  # similar
  #it "should respond to unexecute" do
  #  subject.should respond_to(:unexecute)
  #end
  # better
  it { should respond_to :unexecute }

end

When I run this I get:

CommandFactory
behaves like a command
should respond to #execute
should respond to #unexecute

The idea of the it block so I could get:

CommandFactory
Creates commands which:
behaves like a command
should respond to #execute
should respond to #unexecute

context "Creates commands which:" do
    subject {  factory.command(:foo) }
    it_behaves_like "a command"
end

CommandFactory
  Creates commands which:
    behaves like a command
      should respond to #execute
      should respond to #unexecute