I think a verbalization of "predikit" is a better way to read it. "Predikayte" already has a different meaning, one that could make people think of assertions... essentially the same meaning trouble as "testify," right? :-p
Personally, I think this is all moot, but I'd go with "checkify" or "to-check".
testify
Pro: Only 7 characters long.
Pro: Bunches with related words containing "ify."
Con: Bunches with unrelated words containing "test."
Con: Is a neologism if used in English.
Con: Has non-sequitur homonyms in English (one meaning "claim").
Con: The vocal majority here at Arc Forum seems to dislike it. :-p
predicate
Pro: Bunches with related words containing "icate."
Con: Debatable pronunciation.
"predikayte"
Con: Is a neologism if used in English, I think. It
reinterprets the verb as a verbalization of the "predikit"
version, when "predikit" is actually something of a
nominalized form of "predikayte" in the first
place[Wiktionary]. Is it already used this way?
Con: Has non-sequitur homonyms in English (one meaning
"assume").
"predikit"
Pro: Same as a related term used in English discussion.
"predikahtay"
Con: Has a non-sequitur homonym in Italian (meaning
"preach")[Wiktionary].
Con: Since it has the same spelling as a noun, it may conflict with
other noun-based names (e.g. accessors, local variables).
Con: In English discussion, needs special formatting to look like a
variable name.
checkify
Pro: Bunches with related words containing "check."
Pro: "Check" is a related term that can be dropped casually into
English discussion.
Con: "Check" has many non-sequitur homonyms in English (one
meaning "restrict").
Pro: Bunches with related words contianing "ify."
Con: Is a neologism if used in English.
to-check
Pro: Bunches with related words containing "check."
Pro: "Check" is a related term that can be dropped casually into
English discussion.
Con: "Check" has many non-sequitur homonyms in English (one
meaning "restrict").
Pro: Bunches with related utilities containing "to-".
Con: Is a downright technical term if used in English.
Con: "To check" could be seen as an infinitive form.