OP solved it, closing

Correction in the algorithm for noWords function (edge case) :

// noWords function (edge case):

// - if the text (string) has not letters at all then return true

// - iterate over the characters of the string

// - if none of the characters are letters then return true

// else return false

I'm sorry but why to NOT mutate input object? It doesn't seems to make any difference here except for the random tests failing.
@Chrono79

Good solution!