Delete $CFG->dirroot/composer.lock and $CFG->dirroot/vendor Edit composer.json and change - "moodlehq/behat-extension": "1.0.*" + "moodlehq/behat-extension": "dev-master" Update your behat test environment and run behat with --tags @core_group option The test SHOULD pass Edit group/autogroup.php and add a throw new coding_exception('asdasdasd'); after $editform->display(); Run behat with --tags @core_group option You SHOULD see a failure with a message containing Moodle exception: Edit group/autogroup.php and replace the exception with a echo $imavarandidontexist; Run behat with --tags @core_group option You SHOULD see a failure with a message containing PHP debug message/s found: Edit group/autogroup.php and replace the echo for this, copy & paste to keep the line break: echo 'line 112 of asd/asdasdasd/asd/a/sdasd: call to asdfFFF->Fasdf() line 112 of asd/asdasdasd/asd/a/sdasd: call to asd_fFFF->Fasdf() line 112 of asd/asdasdasd/asd/a/sdasd: call to asdfFFF::Fasdf()'; Run behat with - tags @core_group option# Run behat with -tags @core_group option You SHOULD see a failure with a message containing Other backtraces found Edit group/autogroup.php and replace the echo for a debugging('asd'); Run behat with - tags @core_group option# Run behat with -tags @core_group option You SHOULD see a failure with a message containing Debugging message/s found Edit group/autogroup.php and replace the debugging() message (if is still present) for echo $imavarandidontexist; Reload page and inspect the source code of the notice It SHOULD NOT be wrapped in a <div class="phpdebugmessage"> container