phpbb_convert_30_dbms_to_31 is undefined in this situation and an error is thrown.
Please provide the actual error messages in the future.
Call to undefined function phpbb_convert_30_dbms_to_31 phpbb_test_case_helpers.php line 81
Still not sure how to reproduce this.
You must be using a test config file and the test must not include the functions.php file itself.
Yes. Provide an example of such a test.
Looking through the test cases, it looks like phpbb_cache_null_driver_test doesnt include it.