Fatal error: Uncaught Error: Class 'tests\DatabaseTestCase' not found in /var/www/html/autocar/vendor/creocoder/yii2-nested-sets/tests/NestedSetsBehaviorTest.php:19 Stack trace: #0 {main} thrown in /var/www/html/autocar/vendor/creocoder/yii2-nested-sets/tests/NestedSetsBehaviorTest.php on line 19