title: Create new stub method that checks if the method exists in Rspec
body: <p>I would like to create some especial stub methods <code>stub_check</code> and <code>stub_chain_check</code> that ensure the method exists.</p>
  
  <p>For example:</p>
  
  <pre><code>#spec/controllers/payments_controller_spec.rb`
  
  describe PaymentsController do
    it "makes a payment" do
      # Ensure method exists, Payment.new.respond_to?(:pay)
      # the API of Payment can change and tests will pass
      raise "Stubbing wrong method Payment#pay method doesn't exists" unless Payment.new.respond_to?(:pay)
      Payment.any_instance.stub(pay: true) # We can stub method now
      # Code...
    end
  end
  </code></pre>
  
  <p>But I would like to to somwthing like <code>Payment.stub_check(pay: true)</code></p>