require 'date'

def next_working_day(n = 1, from: Date.today)
        date = from
        i = 0
        while i < n
                i += 1 unless date.next_day.saturday? || date.next_day.sunday?
                date = date.next_day
        end
        date
end

p next_working_day
p next_working_day(from: Date.today)
p next_working_day(1, from: Date.today)
p next_working_day(2, from: Date.today)
p next_working_day(3, from: Date.today)
p next_working_day(4, from: Date.today)
p next_working_day(5, from: Date.today)
p next_working_day(6, from: Date.today)
p next_working_day(7, from: Date.today)

p '---'

d = Date.today
p "before #{d}"
p next_working_day(from: d)
p "after #{d}"