require 'test/unit' require File.dirname(__FILE__) + '/../../lib/active_support/core_ext/enumerable' Payment = Struct.new(:price) class EnumerableTests < Test::Unit::TestCase def test_group_by names = %w(marcel sam david jeremy) klass = Class.new klass.send(:attr_accessor, :name) objects = (1..50).inject([]) do |people,| p = klass.new p.name = names.sort_by { rand }.first people << p end objects.group_by {|object| object.name}.each do |name, group| assert group.all? {|person| person.name == name} end end def test_sums payments = [ Payment.new(5), Payment.new(15), Payment.new(10) ] assert_equal 30, payments.sum(&:price) assert_equal 60, payments.sum { |p| p.price * 2 } end end