require File.expand_path('../../../spec_helper', __FILE__)
require File.expand_path('../fixtures/classes', __FILE__)

describe "Enumerable#max_by" do
  ruby_version_is '1.8.7' do
    platform_is_not :enumerable_java do
      it "returns an enumerator if no block" do
        EnumerableSpecs::Numerous.new(42).max_by.should be_an_instance_of(enumerator_class)
      end
    end

    it "returns nil if #each yields no objects" do
      EnumerableSpecs::Empty.new.max_by {|o| o.nonesuch }.should == nil
    end


    it "returns the object for whom the value returned by block is the largest" do
      EnumerableSpecs::Numerous.new(*%w[1 2 3]).max_by {|obj| obj.to_i }.should == '3'
      EnumerableSpecs::Numerous.new(*%w[three five]).max_by {|obj| obj.length }.should == 'three'
    end

    it "returns the object that appears first in #each in case of a tie" do
      a, b, c = '1', '2', '2'
      EnumerableSpecs::Numerous.new(a, b, c).max_by {|obj| obj.to_i }.should equal(b)
    end

    it "uses max.<=>(current) to determine order" do
      a, b, c = (1..3).map{|n| EnumerableSpecs::ReverseComparable.new(n)}

      # Just using self here to avoid additional complexity
      EnumerableSpecs::Numerous.new(a, b, c).max_by {|obj| obj }.should == a
    end

    platform_is_not :enumerable_java do
      it "is able to return the maximum for enums that contain nils" do
        enum = EnumerableSpecs::Numerous.new(nil, nil, true)
        enum.max_by {|o| o.nil? ? 0 : 1 }.should == true
        enum.max_by {|o| o.nil? ? 1 : 0 }.should == nil
      end
    end
  end
end