mh-test-completion

mh-test-completion is an alias for `test-completion' in `mh-compat.el'.

(mh-test-completion STRING COLLECTION &optional PREDICATE)

Return non-nil if STRING is a valid completion.
Takes the same arguments as `all-completions' and `try-completion'.
If COLLECTION is a function, it is called with three arguments:
the values STRING, PREDICATE and `lambda'.