alias_method is private on Ruby 2.3 and 2.4

Author: hsbt

tests/json_generator_test.rb

@@ -395,7 +395,7 @@ def to_s; self; end
     def test_string_ext_included_calls_super
       included = false
 
-      Module.alias_method(:included_orig, :included)
+      Module.send(:alias_method, [:included_orig, :included])
       Module.remove_method(:included)
       Module.define_method(:included) do |base|
         included_orig(base)
@@ -410,7 +410,7 @@ def test_string_ext_included_calls_super
     ensure
       if Module.private_method_defined?(:included_orig)
         Module.remove_method(:included) if Module.method_defined?(:included)
-        Module.alias_method(:included, :included_orig)
+        Module.send(:alias_method, [:included, :included_orig])
         Module.remove_method(:included_orig)
       end
     end