require File.dirname(__FILE__) + '/../abstract_unit' Payment = Struct.new(:price) class SummablePayment < Payment def +(p) self.class.new(price + p.price) end end 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 assert_equal 30, [5, 15, 10].sum assert_equal 30, [5, 15, 10].sum { |i| i } assert_equal 'abc', %w(a b c).sum assert_equal 'abc', %w(a b c).sum { |i| i } 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 } payments = [ SummablePayment.new(5), SummablePayment.new(15) ] assert_equal SummablePayment.new(20), payments.sum assert_equal SummablePayment.new(20), payments.sum { |p| p } end def test_nil_sums assert_raise(TypeError) { [5, 15, nil].sum } payments = [ Payment.new(5), Payment.new(15), Payment.new(10), Payment.new(nil) ] assert_raise(TypeError) { payments.sum(&:price) } assert_equal 60, payments.sum { |p| p.price.to_i * 2 } end def test_empty_sums assert_equal 0, [].sum assert_equal 0, [].sum { |i| i } assert_equal Payment.new(0), [].sum(Payment.new(0)) end def test_index_by payments = [ Payment.new(5), Payment.new(15), Payment.new(10) ] assert_equal( {5 => payments[0], 15 => payments[1], 10 => payments[2]}, payments.index_by(&:price) ) end end