Rcov: Why is this code not being considered covered?

Question

Here's my controller:

class MyController < ApplicationController
  include MyHelper

  def index
    get_list_from_params do |list|
      @list = list
      respond_to do |format|
        format.html
        format.xml  { render :xml => @list }
        format.json { render :json => @list }
      end
    end
  end
end

...the helper that it's based on:

module MyHelper
  def get_list_from_params(param = :id, &on_success)
    raw_id = params[param]
    begin
      id = Integer(raw_id)
    rescue
      render :template => "invalid_id", :locals => {:id => raw_id }
    else
      yield MyList.new(id)
    end
  end
end

...and my functional test (which is using Shoulda):

class MyControllerTest < ActionController::TestCase
  context "MyController index" do
    setup do
      get :index
    end

    should_respond_with :success
  end
end

EDIT My rcov rake is exactly the same as the one listed in the official FAQ: eigenclass.org

RCov (0.9.7.1) lists every line in the controller up to "def index" as green, and every line after that (including all of the "end"s) as red/unexecuted. I know that when my test actually executes, it does execute the code successfully.

Why does RCov give unintuitive results? Is there something I'm missing here?

Answer 1

My guess is you are using ruby 1.9? Rcov does not support ruby 1.9 and produces impredictable results. Use SimpleCov instead.

Answer 2

My guess is that rcov only considers code run in actual test-cases as "covered" by a test. your call to "get index" is not technically in a test-case, but in the setup block. shoulda has interesting scope-issues with setup and perhaps rcov simply isn't smart enough to realise that.

Try putting the code into a test case block (see below) - just to see if that changes things. Note: I don't think you should have to run your tests like this - it's just to see if it works.

context "MyController index" do
  should "respond with success" do
    get :index     
    assert_response :success
  end
end