While it's not explicitly stated, Bernie wanted you to use the vote_up method to increment the two comments from their initial score of 1 and then test that the link score was equal to the sum of the two comment scores.

it "updates its cumulative score when a comment gets a score" do
  comment_1 = @link.comments.first
  comment_1.vote_up
       
  comment_2 = FactoryGirl.create(:comment, link:@link)
  2.times { comment_2.vote_up }
  
  @link.score.should == 5
 end