In MDL-81698 (various PHPUnit cleanups) it was detected that we had the test_grade_grade_set_locked() test commented out with comment:

Disabling this test: the set_locked() arguments have been modified, rendering these tests useless until they are re-written

And, because having commented tests is not good we proceeded to un-comment it and mark it as skipped, with comment:

Skip this test because set_locked() arguments have been modified, rendering these tests useless until they are re-written. Note this comes from MDL-32323 (2012!).

So, this issue is about to:

1. Decide if the test should be removed or amended to cover the grade_grade::set_locked() method.
2. Proceed with the decision.

Ciao