Ruby - Fail statement/Guard Condition returning nil - arrays

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