scoring_peredictions

gistfile1.txt

      Write a method that accepts two arguments: an Array of five guesses for 
      finalists in a race and an Array of the five actual finalists. Each
      position in the lists matches a finishing position in the race, so first
      place corresponds to index 0. Return an Integer score of the predictions:
      0 or more points. Correctly guessing first place is worth 15 points,
      second is worth 10, and so on down with 5, 3, and 1 point for fifth
      place. It's also worth 1 point to correctly guess a racer that finishes
      in the top five but to have that racer in the wrong position.

scoring_help.rb

require "race"

describe "Race::score" do
  let(:winners) { %w[First Second Third Fourth Fifth] }

  def correct_guesses(*indexes)
    winners.map.with_index { |w, i| indexes.include?(i) ? w : "Wrong" }
  end

  it "add points for each position" do
    Race.score(winners, winners).should eq(15 + 10 + 5 + 3 + 1)
  end

  it "gives 0 points for no correct guesses" do
    all_wrong = correct_guesses  # none correct
    Race.score(all_wrong, winners).should eq(0)
  end

  it "gives 15 points for first place" do
    Race.score(correct_guesses(0), winners).should eq(15)
  end

  it "gives 10 points for second place" do
    Race.score(correct_guesses(1), winners).should eq(10)
  end

  it "gives 5 points for third place" do
    Race.score(correct_guesses(2), winners).should eq(5)
  end

  it "gives 3 points for fourth place" do
    Race.score(correct_guesses(3), winners).should eq(3)
  end

  it "gives 1 point for fifth place" do
    Race.score(correct_guesses(4), winners).should eq(1)
  end

  it "gives one point for a correct guess in the wrong place" do
    guesses = correct_guesses(0)
    guesses.unshift(guesses.pop)  # shift positions by one
    Race.score(guesses, winners).should eq(1)
  end

  it "score positional and misplaced guesses at the same time" do
    guesses                = correct_guesses(0, 3)
    guesses[3], guesses[4] = guesses[4], guesses[3]
    Race.score(guesses, winners).should eq(15 + 1)
  end
end