From 49f44b1ddd0c0da2cb734d91a441c3bbaf11ecf0 Mon Sep 17 00:00:00 2001
From: Mike Dalessio <mike@37signals.com>
Date: Tue, 10 Feb 2026 09:21:22 -0500
Subject: Add ruby specs for UnboundMethod#== with included/extended modules
 [Bug #21873]

https://bugs.ruby-lang.org/issues/21873
---
 spec/ruby/core/unboundmethod/equal_value_spec.rb | 30 ++++++++++++++++++++++++
 spec/ruby/core/unboundmethod/fixtures/classes.rb | 16 +++++++++++++
 2 files changed, 46 insertions(+)

(limited to 'spec/ruby/core')

diff --git a/spec/ruby/core/unboundmethod/equal_value_spec.rb b/spec/ruby/core/unboundmethod/equal_value_spec.rb
index c9f7ad45da..c2982766e9 100644
--- a/spec/ruby/core/unboundmethod/equal_value_spec.rb
+++ b/spec/ruby/core/unboundmethod/equal_value_spec.rb
@@ -35,6 +35,12 @@ describe "UnboundMethod#==" do
 
     @method_one = UnboundMethodSpecs::Methods.instance_method(:one)
     @method_two = UnboundMethodSpecs::Methods.instance_method(:two)
+
+    @mixin = UnboundMethodSpecs::Mixin.instance_method(:mixin_method)
+    @includer_base = UnboundMethodSpecs::IncluderBase.new.method(:mixin_method).unbind
+    @includer_child = UnboundMethodSpecs::IncluderChild.new.method(:mixin_method).unbind
+    @extender_base = UnboundMethodSpecs::ExtenderBase.method(:mixin_method).unbind
+    @extender_child = UnboundMethodSpecs::ExtenderChild.method(:mixin_method).unbind
   end
 
   it "returns true if objects refer to the same method" do
@@ -91,6 +97,30 @@ describe "UnboundMethod#==" do
     (@includer == @includee).should == true
   end
 
+  ruby_version_is "4.1" do
+    it "returns true if same method is present in an object through module inclusion" do
+      (@mixin == @includer_base).should == true
+      (@includer_base == @mixin).should == true
+
+      (@mixin == @includer_child).should == true
+      (@includer_child == @mixin).should == true
+
+      (@includer_base == @includer_child).should == true
+      (@includer_child == @includer_base).should == true
+    end
+
+    it "returns true if same method is present in an object through module extension" do
+      (@mixin == @extender_base).should == true
+      (@extender_base == @mixin).should == true
+
+      (@mixin == @extender_child).should == true
+      (@extender_child == @mixin).should == true
+
+      (@extender_base == @extender_child).should == true
+      (@extender_child == @extender_base).should == true
+    end
+  end
+
   it "returns false if both have same Module, same name, identical body but not the same" do
     class UnboundMethodSpecs::Methods
       def discard_1; :discard; end
diff --git a/spec/ruby/core/unboundmethod/fixtures/classes.rb b/spec/ruby/core/unboundmethod/fixtures/classes.rb
index 28d8e0a965..bb3f7e0849 100644
--- a/spec/ruby/core/unboundmethod/fixtures/classes.rb
+++ b/spec/ruby/core/unboundmethod/fixtures/classes.rb
@@ -80,6 +80,22 @@ module UnboundMethodSpecs
     end
   end
 
+  module Mixin
+    def mixin_method; end
+  end
+
+  class IncluderBase
+    include Mixin
+  end
+
+  class IncluderChild < IncluderBase; end
+
+  class ExtenderBase
+    extend Mixin
+  end
+
+  class ExtenderChild < ExtenderBase; end
+
   class A
     def baz(a, b)
       return [__FILE__, self.class]
-- 
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