From Moodle 3.2 we get the following error when trying to access to Acceptance testing (from Development menu):

( ! ) Fatal error: Class 'Behat\Mink\Selector\ExactNamedSelector' not found in /moodle/lib/behat/classes/exact_named_selector.php on line 33

Call Stack # Time Memory Function Location 1 0.0048 232632 {main}( ) .../index.php*:0 2 3.6353 14999280 tool_behat::stepsdefinitions( ) .../index.php:42 3 3.6353 14999816 behat_command::behat_setup_problem( ) .../locallib.php:53 4 3.6365 14991312 behat_command::output_msg( ) .../behat_command.php:177 5 3.6365 14991408 moodle_page->get_renderer( ) .../behat_command.php:251 6 3.6365 14991504 theme_config->get_renderer( ) .../pagelib.php:861 7 3.6365 14991504 theme_overridden_renderer_factory->get_renderer( ) .../outputlib.php:2120 8 3.6365 14991504 renderer_factory_base->standard_renderer_classnames( ) .../outputfactories.php:389 9 3.6373 15001144 include_once( '/moodle/admin/tool/behat/renderer.php' ) .../outputfactories.php:201 10 3.6377 15003496 require_once( '/moodle/lib/behat/classes/behat_selectors.php' ) .../renderer.php:28 11 3.6380 15008080 require_once( '/moodle/lib/behat/classes/exact_named_selector.php' ) .../behat_selectors.php:*26

With previous versions (like Moodle 3.1) it was not necessary to configure acceptance testing. If there were not configured, some information was shown.