Introduce test to demonstrate regression caused by da99a2a2

activerecord/test/cases/type/type_map_test.rb

@@ -124,6 +124,16 @@ module ActiveRecord
         assert_equal mapping.lookup(3), 'string'
         assert_kind_of Type::Value, mapping.lookup(4)
       end
+
+      def test_aliases_are_not_improperly_cached
+        mapping = HashLookupTypeMap.new
+
+        mapping.register_type("foo") { |*args| args.join("-") }
+        mapping.alias_type("bar", "foo")
+
+        assert_equal "bar-1-2-3", mapping.lookup("bar", 1, 2, 3)
+        assert_equal "foo-1-2-3", mapping.lookup("foo", 1, 2, 3)
+      end
     end
   end
 end