1 files changed, 15 insertions, 0 deletions
diff --git a/spec/ruby/core/integer/plus_spec.rb b/spec/ruby/core/integer/plus_spec.rb
index be626c3305..511a436872 100644
--- a/spec/ruby/core/integer/plus_spec.rb
+++ b/spec/ruby/core/integer/plus_spec.rb
@@ -40,4 +40,19 @@ describe "Integer#+" do
       -> { @bignum + :symbol}.should raise_error(TypeError)
     end
   end
+
+  it "can be redefined" do
+    code = <<~RUBY
+      class Integer
+        alias_method :old_plus, :+
+        def +(other)
+          self - other
+        end
+      end
+      result = 1 + 2
+      Integer.alias_method :+, :old_plus
+      print result
+    RUBY
+    ruby_exe(code).should == "-1"
+  end
 end