Delegate to `eql?` [Fix GH-1564]

* lib/delegate.rb (eql?): Delegate to `eql?` of the inner object.
  based on the patch by giginet <giginet.net@gmail.com>.
  [ruby-core:76950] [Bug #12684]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59167 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 56 insertions, 4 deletions

diff --git a/lib/delegate.rb b/lib/delegate.rb
index fa70848134..c5a94a5d31 100644
--- a/lib/delegate.rb
+++ b/lib/delegate.rb
@@ -40,7 +40,7 @@ class Delegator < BasicObject
   kernel = ::Kernel.dup
   kernel.class_eval do
     alias __raise__ raise
-    [:to_s, :inspect, :=~, :!~, :===, :<=>, :eql?, :hash].each do |m|
+    [:to_s, :inspect, :=~, :!~, :===, :<=>, :hash].each do |m|
       undef_method m
     end
     private_instance_methods.each do |m|
@@ -146,6 +146,14 @@ class Delegator < BasicObject
   end
 
   #
+  # Returns true if two objects are considered of equal value.
+  #
+  def eql?(obj)
+    return true if obj.equal?(self)
+    obj.eql?(__getobj__)
+  end
+
+  #
   # Delegates ! to the \_\_getobj\_\_
   #
   def !
diff --git a/spec/rubyspec/library/delegate/delegator/eql_spec.rb b/spec/rubyspec/library/delegate/delegator/eql_spec.rb
index 937629f73e..7d101eb262 100644
--- a/spec/rubyspec/library/delegate/delegator/eql_spec.rb
+++ b/spec/rubyspec/library/delegate/delegator/eql_spec.rb
@@ -2,10 +2,34 @@ require File.expand_path('../../../../spec_helper', __FILE__)
 require File.expand_path('../../fixtures/classes', __FILE__)
 
 describe "Delegator#eql?" do
-  it "is delegated" do
+  it "returns true when compared with same delegator" do
     base = mock('base')
     delegator = DelegateSpecs::Delegator.new(base)
-    base.should_receive(:eql?).with(42).and_return(:foo)
-    delegator.eql?(42).should == :foo
+
+    delegator.eql?(delegator).should be_true
+  end
+
+  it "returns true when compared with the inner object" do
+    base = mock('base')
+    delegator = DelegateSpecs::Delegator.new(base)
+
+    delegator.eql?(base).should be_true
+  end
+
+  it "returns false when compared with the delegator with other object" do
+    base = mock('base')
+    other = mock('other')
+    delegator0 = DelegateSpecs::Delegator.new(base)
+    delegator1 = DelegateSpecs::Delegator.new(other)
+
+    delegator0.eql?(delegator1).should be_false
+  end
+
+  it "returns false when compared with the other object" do
+    base = mock('base')
+    other = mock('other')
+    delegator = DelegateSpecs::Delegator.new(base)
+
+    delegator.eql?(other).should be_false
   end
 end
diff --git a/test/test_delegate.rb b/test/test_delegate.rb
index 18c175c719..48bf9cdbf0 100644
--- a/test/test_delegate.rb
+++ b/test/test_delegate.rb
@@ -3,6 +3,14 @@ require 'test/unit'
 require 'delegate'
 
 class TestDelegateClass < Test::Unit::TestCase
+  module PP
+    def mu_pp(obj)
+      str = super
+      str = "#<#{obj.class}: #{str}>" if Delegator === obj
+      str
+    end
+  end
+
   module M
     attr_reader :m
   end
@@ -119,6 +127,18 @@ class TestDelegateClass < Test::Unit::TestCase
     assert_equal([:bar], s.methods(false))
   end
 
+  def test_eql?
+    extend PP
+    s0 = SimpleDelegator.new("foo")
+    s1 = SimpleDelegator.new("bar")
+    s2 = SimpleDelegator.new("foo")
+    assert_operator(s0, :eql?, s0)
+    assert_operator(s0, :eql?, "foo")
+    assert_operator(s0, :eql?, s2)
+    assert_not_operator(s0, :eql?, s1)
+    assert_not_operator(s0, :eql?, "bar")
+  end
+
   class Foo
     private
     def delegate_test_private