1. Create a course with multiple activities(quiz and assignments).
2. Set the course completion as the completion of several activities.
3. Enroll some students to this course
4. Let these students to complete all these activities in more than one attempts with FAILURE (grade < passgrade) in the first and PASS grade in the second/third ones.
5. Check the completion report at page /report/completion/index.php?course=XX
6. Download the completion report as a CSV file.
7. Check the completion dates. 
   PROBLEM: Completion dates are the first completion dates independent of PASS or FAIL grade. They supposed to be the last grading date.

The completed (including FAILED) activities are not picked up by the cron() function of  completion_criteria_activity.php