Ruby - Fail statement/Guard Condition returning nil

Question

I'm trying to improve the release_bike method. I have gone into irb, and the first guard condition works, and the release_working_bikes work, but the second guard condition keeps on return nil in irb, even when I run a feature test and know that there is only a broken bike available.

Is there something wrong with the way I'm phrasing my second fail line, or is there a flaw in broken_bikes ?

The release_bike method should work as follows; if there are no bikes in the docking station, then there should be a warning saying - No bikes available if there are bikes in the docking station, but they are ALL broken, then there should be a warning saying - No working bikes available if there are some working bikes, then release_bike should release one of the workign bikes.

Below are the two classes, that are involved;

require_relative 'bike'
class DockingStation
  DEFAULT_CAPACITY = 20
  attr_reader :capacity, :bikes

  def initialize(capacity = DEFAULT_CAPACITY)
    @bikes = []
    @capacity = capacity

  end

  def release_bike
    fail 'No bikes available' if empty?
    fail 'No working bikes available' unless broken_bikes
    release_working_bikes

  end

  def dock(bike)
    fail 'Docking Station Full' if full?
    @bikes << bike
  end

  private

  def working_bikes
    @bikes.each { |bike| return bike unless bike.broken? }
  end

  def broken_bikes
    not_working = []
    not_working << @bikes.each { |bike| return bike if bike.broken? }
    not_working.empty?
  end

  def release_working_bikes
    bike = working_bikes
    @bikes.delete(bike)
  end

  def full?
    @bikes.count >= @capacity
  end

  def empty?
    @bikes.empty?
  end

end



class Bike
  attr_accessor :broken

  def initialize
    @broken = false
  end

  def working?
    @working
  end

  def report_broken
    @broken = true
  end

  def broken?
    @broken
  end

end

Answer 1

As already pointed out in comments, you're trying to check if all bikes are broken, so why not name your method all_bikes_broken? . See comments in code.

require_relative 'bike'
class DockingStation
  DEFAULT_CAPACITY = 20
  attr_reader :capacity, :bikes

  def initialize(capacity = DEFAULT_CAPACITY)
    @bikes = []
    @capacity = capacity

  end

  def release_bike
    fail 'No bikes available' if empty?
    fail 'No working bikes available' unless all_bikes_broken?
    release_working_bikes

  end

  def dock(bike)
    fail 'Docking Station Full' if full?
    @bikes << bike
  end

  private

  def working_bikes
    #this will select only bikes which are NOT broken
    @bikes.reject{ |bike| bike.broken? }
  end

  def all_bikes_broken?
    #this is shorthand for @bikes.all?{ |bike| bike.broken? }
    #it says send  :broken? method to each instance of bike.
    #.all? returns true only if all instances return true, otherwise false.
    @bikes.all?(&:broken?)
  end

  def release_working_bikes
    bike = working_bikes
    @bikes.delete(working_bikes.first)
    #or you could do .last but order probably doesn't matter here.
  end

  def full?
    @bikes.count >= @capacity
  end

  def empty?
    @bikes.empty?
  end

end


class Bike
  attr_accessor :broken

  def initialize
    @broken = false
  end

  def working?
    @working
  end

  def report_broken
    @broken = true
  end

  def broken?
    @broken
  end

end