testy vs irritable

testy and irritable both are adjectives.

Word	Noun	Adjective	Verb	Adverb
testy	No	Yes	No	No
irritable	No	Yes	No	No

As adjectives, testy and irritable are synonyms defined as:

Other synonyms of testy include cranky, fractious, nettlesome, peckish, peevish, pettish, petulant, scratchy, techy, tetchy.

testy (adjective)	irritable (adjective)
easily irritated or annoyed	easily irritated or annoyed
	capable of responding to stimuli
	abnormally sensitive to a stimulus