Merge pull request #30324 from koic/fix_cant_modify_frozen_string_in_ar_test

Fix `can't modify frozen String` error in an AR test

activerecord/test/cases/adapter_test.rb

@@ -288,11 +288,11 @@ def test_select_methods_passing_a_relation
       def test_log_invalid_encoding
         error = assert_raises RuntimeError do
           @connection.send :log, "SELECT 'ы' FROM DUAL" do
-            raise "ы".force_encoding(Encoding::ASCII_8BIT)
+            raise "ы".dup.force_encoding(Encoding::ASCII_8BIT)
           end
         end
 
-        assert_not_nil error.message
+        assert_equal "ы", error.message
       end
     end
   end