For this test you'll need a course with at least one grade item, ie an assessable activity.
1) While viewing a course click on Grades in Course administration.
2) Use the gradebook navigation drop down to go to the Categories and items page.
3) Click on "Add category" and create a category.
4) Click on the move icon next to a grade item. It is the little up/down arrow icon.
5) Click on the box that appears within your category to place your grade item within your category.
6) Use the gradebook navigation drop down to go to the user report. View the user report for a user and verify that the grade item now appears within your category.