gistfile1.rb

# How I might test this helper

module SomeHelper
  def title(page_title)
    content_for(:title) { page_title }
  end
end

describe SomeHelper
  include SomeHelper
  
  describe "title" do
    # We've made a fake content_for that is super easy to test because it 
    # immediately yields the block.
    def content_for(section)
      yield
    end
    
    # ensure it puts it in the right "section"
    it "should call content_for with section title" do
      should_receive(:content_for).with(:title)
      title('testing')
    end

    # ensure the argument is passed
    it "should call content_for with the page_title attribute in a block" do
      # We could figure out where content_for stores it's blocks but we'd be
      # coupling ourselves to it's implementation. We can trust that content_for
      # works, we only need to test our usage of it.
      title('testing').should == 'testing'
    end

    # that's all the logic in the method...
  end
end