Foreman divides up units of work evenly amongst workers

foreman.rb

class Foreman
  attr_accessor :units_of_work, :workers_count

  def initialize attrs = {}
    @units_of_work = attrs[:units_of_work]
    @workers_count = attrs[:workers_count]
  end

  def fair_shares
    even_shares = Array.new(@workers_count) { @units_of_work / @workers_count }
    if (remainder = (@units_of_work - even_shares.reduce(:+))) != 0
      0.upto(remainder - 1).each { |i| even_shares[i] += 1 }
    end
    even_shares
  end
end

describe Foreman do
  describe "#fair_shares" do
    context "when dealing with evenly splittable amounts of work / worker" do
      let(:units_of_work) { 10 }
      let(:workers_count) { 2 }
      let(:foreman) { described_class.new units_of_work: units_of_work, workers_count: workers_count }

      it "returns an array of evenly split work units" do
        foreman.fair_shares.should == [5, 5]
      end

      it "returns an array of work shares that sum to the total amount required" do
        foreman.fair_shares.reduce(:+).should == units_of_work
      end
    end

    context "when dealing with non-evenly splittable amounts of work / worker" do
      let(:units_of_work) { 11 }
      let(:workers_count) { 2 }
      let(:foreman) { described_class.new units_of_work: units_of_work, workers_count: workers_count }

      it "returns an array of evenly split work units, filling in the differences as evenly as possible" do
        foreman.fair_shares.should == [6, 5]
      end

      it "returns an array of work shares that sum to the total amount required" do
        foreman.fair_shares.reduce(:+).should == units_of_work
      end
    end

    context "when dealing with an even more complete, non-evenly splittable amounts of work / worker" do
      let(:units_of_work) { 19 }
      let(:workers_count) { 7 }
      let(:foreman) { described_class.new units_of_work: units_of_work, workers_count: workers_count }

      it "returns an array of evenly split work units, filling in the differences as evenly as possible" do
        foreman.fair_shares.should == [3, 3, 3, 3, 3, 2, 2]
      end

      it "returns an array of work shares that sum to the total amount required" do
        foreman.fair_shares.reduce(:+).should == units_of_work
      end
    end
  end
end