Create a course module. Edit the function course_delete_module in course/lib.php by copying the first occurrence of "throw new exception ..." in this issues diff and placing it after the declaration of $modulename. Attempt to delete the module and ensure exception is thrown as expected. Replace this "throw new exception ..." with the next one and continue until you have gone through all of them in this diff. Remove the changes you have done from course/lib.php and ensure you can delete the module instance.