How Do You Spell TESTEST?
Pronunciation: [tˈɛstəst] (IPA) 
The word "testest" violates English spelling conventions, as there is no double "s" following a long vowel sound in a comparative form. However, using the International Phonetic Alphabet, the spelling of "testest" can be explained as /ˈtɛst.ɛst/, with the initial "e" pronounced as a short "e" and the following "e" pronounced as a schwa. This word is not recognized in standard English, and the correct comparative form of "test" is simply "tester."
