spec.rb

describe 'conversations/base' do
  subject do
    Timecop.freeze(10.minutes.ago) { @conversation = FactoryGirl.create(:conversation) }
    Timecop.return
    @conversation
  end

  before :each do
    assign(:object, subject)
  end

  it 'expire the conversation when the conversation is updated' do
    expect {
      subject.update_attribute(:name, 'test')
      subject.reload
    }.to change(self, :render)
  end

end

Time now UTC: 2013-07-25 14:20:14 UTC
SPEC inspect: #<Conversation id: 1, project_id: 1, user_id: 1, name: "The Master Plan", created_at: "2013-07-25 14:10:10", updated_at: "2013-07-25 14:10:10">