Add spec for keyword argument caller to reuse Hash

in Ruby version 3.0.0

Author: wildmaples

spec/ruby/language/method_spec.rb

@@ -817,6 +817,17 @@ def m(a, **k) [a, k] end
         m(1, a: 2, b: 3).should == [1, {a: 2, b: 3}]
         -> { m("a" => 1, b: 2) }.should raise_error(ArgumentError)
       end
+
+      evaluate <<-ruby do
+          def m(a)
+            a.delete(:one); a
+          end
+        ruby
+        h = { one: 1, two: 2 }
+
+        m(**h).should == { two: 2 }
+        m(**h).should equal(h)
+      end
     end
 
     evaluate <<-ruby do