The Wesley Date Challenge

gistfile1.rb

# Uses 1.9.2
# Makes use of existing day names in Date class
# Demeter is happy
# Support full and abbreviated names
# Doesn't use seconds (avoids error scenarios when crossing DST & leap-seconds)

class DDate < Date
  def self.next(target_dayname)
    target_wday = ABBR_DAYNAMES.index { |dayname| target_dayname =~ Regexp.new(dayname) }
    diff = target_wday - today.wday
    diff += 7 if diff < 0

    today + diff
  end
end

# See how she runs
{ "Monday"    => Date.civil(2011, 05, 30),
  "Tuesday"   => Date.civil(2011, 05, 31),
  "Wednesday" => Date.civil(2011, 06, 01),
  "Thursday"  => Date.civil(2011, 05, 26),
  "Friday"    => Date.civil(2011, 05, 27),
  "Saturday"  => Date.civil(2011, 05, 28),
  "Sunday"    => Date.civil(2011, 05, 29)
}.each do |name, date|
  result = DDate.next name
  message = result == date ? "OK" : "Expected #{date}"
  puts "#{name}: #{result} #{message}"
end