DelegateClass instance doesn't eql? itself

delegate_eql.rb

require 'test/unit'
require 'delegate'

# These tests demonstrate some unexpected (to me)
# behavior of a class created by DelegateClass.
# An instance of a DelegateClass created class does not eql? itself.
#
# The WidgetTests all pass.
# The comparison and eql WidgetWrapperTests fail.
# ruby 1.9.3p0 (2011-10-30 revision 33570) [x86_64-darwin11.2.0]

class Widget
end

class WidgetWrapper < DelegateClass(Widget)
end

# no surprises here
class WidgetTests < Test::Unit::TestCase
  def setup
    @widget = Widget.new
  end

  def test_equal_operator
    assert @widget == @widget
  end
  def test_equal
    assert @widget.equal?(@widget)
  end
  def test_comparison
    assert_equal 0, (@widget <=> @widget)
  end
  def test_eql
    assert @widget.eql?(@widget)
  end
end

# interesting results...
class WidgetWrapperTests < Test::Unit::TestCase
  def setup
    @wrapper = WidgetWrapper.new(Widget.new)
  end

  def test_equal_operator
    assert @wrapper == @wrapper
  end
  def test_equal
    assert @wrapper.equal?(@wrapper)
  end
  def test_comparison
    assert_equal 0, (@wrapper <=> @wrapper)
  end
  def test_eql
    assert @wrapper.eql?(@wrapper)
  end
end

Thanks. It was useful for us to find out why our spec fails.