You might feel a bit testy before taking a test, but test and testy are unrelated. Feeling testy is like being peeved, annoyed, or irritated.

The adjective testy is associated with being irritable and on edge. If you find yourself frustrated and becoming impatient, you might make a testy remark like “What the heck is taking so long?” If a family member is acting particularly cranky over breakfast, you might say, “Well, aren’t you testy this morning!” However, a comment like that could be met with a testy reply such as “Mind your own business!”

Definitions of testy

adj easily irritated or annoyed

cranky, fractious, irritable, nettlesome, peckish, peevish, pettish, petulant, scratchy, techy, tetchy
having an irritable and unpleasant disposition