PHPUnit Run mdk phpunit -r -s mod_assign (if using MDK ) or vendor/bin/phpunit --testsuite mod_assign_testsuite . Confirm that there are no error nor failures. Manual testing Login as admin. Navigate to Site administration ► Users ► Permissions ► User policies. Check all items in showuseridentity . Create a user and add special characters to all fields, where appropriate. Try adding characters such as & ' " ¢ £ © € ¥ ® < > . For the user's ID number, try setting it to something like <someid>&idnumber;</someid> . Create a course with an assignment. Enrol that user into the course. Navigate to the assignment and go to the grading form. Confirm that the page renders okay. Confirm that an error dialogue is not being displayed.