Add test to grade-school
Add test to grade-school

tejasbubane/xecmascript,arthurchipdean/xecmascript,arthurchipdean/xecmascript,MattH-be/ecmascript,exercism/xecmascript,exercism/xecmascript,MattH-be/ecmascript,tejasbubane/xecmascript