white box controller spec

gistfile1.rb

describe MessagesController do 
  describe "POST create" do
    let(:message) { mock_model(Message).as_null_object }
    
    before do 
      Message.stub(:new).and_return(message)
    end
  
    it "creates a new message" do 
      Message.should_receive(:new).
        with("text" => "a quick brown fox")
        .and_return(message)
      post :create, :message => { "text" => "a quick brown fox" }
    end

    it "saves the message" do 
      message.should_receive(:save)
      post :create
    end
  end
end