If you split this condition into two the result now lacks prefix and will not work with nested models.

You would have in example {prefix}{table_name}.{field_name} is null, {field_name} {self.direction}.

The second field_name does not have the prefix.

Of course, I must mention that without this case, the test related to nested models will also pass correctly. Can you give an example of a possible error that may occur? Thanks