The neologism [ᴺQ.] tyestima “testable” appeared in by Helge Fauskanger’s Neo-Quenya New Testament (NQNT), but it is almost certainly a typo on his part, since he used the verb [ᴱQ.] tyasta- for “(put to the) test” elsewhere in his work. I would render this neologism as tyastaima, in keeping with Tolkien’s later usage of the suffix -ima with weak verbs.