Why is my class variable still nil after I assign it? (Ruby) - ruby

Question

According to my test, client_1 should be a client class which I have used to see if I can output and put it. I need to use #output variable in my client class is STILL NIL, but I assign it with the capture_output method in my client class.
#war_server.client_keys(0).puts("Hello Frodo") #works
temp_holder = client_1.capture_output #store output from server to temp holder
puts "Here is the captured input from client_1! : #{temp_holder}"#works
puts #client_1.output #DOES NOT WORK. But it should because I assin it in my class and use a reader definition
Here's the code for my classes and test. Thanks!
require 'minitest/autorun'
require 'socket'
require_relative 'WarGame_Class.rb'
require_relative 'ModifiedPlayer_Class.rb'
require_relative 'DeckClass.rb'
class WarServer
def initialize(host, port)
#socket_server = TCPServer.new(host, port)
#players = [Player.new, Player.new]
#deck = CardDeck.new
#deck.deal_cards(#players[0].cards, #players[1].cards)
game = WarGame.new
#clients = {} # keys are sockets, values are players
end
def client_keys(key)
#clients.keys[key] # this should work
end
def input #input reader function
#input
end
def close
#socket_server.close
end
def capture_input ##input client to get what they wrote
#input = #clients.keys[0].read_nonblock(1000) # arbitrary max number of bytes
end
def accept_client
#Hash here to link client to player? (or game?)
client = #socket_server.accept
#clients[client] = #players[#clients.size]
# puts "clients key 0: #{#clients.keys[0]}"
puts
# puts "clients values: #{#clients.values}"
if #clients.size == 2
start_game#####################!!!! Starts game if two clients can put client messages in start game
end
end
def start_game ##############!!!
#clients.keys[0].puts "Welcome to War. Please press enter to play your card"
#clients.keys[1].puts "Welcome to War. Please press enter to play your card"
end
end
class MockWarClient
def initialize
#socket = TCPSocket.new('localhost', 2012)
end
def output
#output
end
def input
#input
end
def capture_output #need to add (socket)? How else read from specific socket?
#output = #socket.read_nonblock(1000) # arbitrary max number of bytes
rescue
#output = "capture_output error."
end
def write_input
#input = #war_server.client_keys.write_nonblock(1000)
end
end
class WarServerTest < MiniTest::Unit::TestCase
def setup #This would be like our INITIALIZE Function
#anything is available through out all tests (i.e., instance vars)
#war_server = WarServer.new('localhost', 2012)
end
def teardown
#war_server.close
end
def test_server_capture_output_from_client
client_1 = MockWarClient.new
#war_server.accept_client
client_2 = MockWarClient.new
#war_server.accept_client
#can output #war_server.client_keys, though, if I take out the argument to pass in.
#puts "Test_Server_output #client keys #{#war_server.client_keys(player)}" #cient_1?
puts "Test_Server_output #client keys 0 #{#war_server.client_keys(0)}"
puts "Test_Server_output #client keys 1 #{#war_server.client_keys(1)}"
#war_server.client_keys(0).puts("Hello Frodo")
temp_holder = client_1.capture_output
puts "Here is the captured input from client_1! : #{temp_holder}"
#puts #war_server.input
puts #client_1.output
end
end

Answer 1

client_1 is a local variable, distinct from #client_1. I don't see anywhere in this code where you assign #client_1. Unless there is some code you're not sharing which does this, then #client_1 will evaluate to nil.

Answer 2

#client_1 is an instance variable, which is a variable on the instance of a class and exists for the duration that the object is in existence. In order to assign a value to an instance variable, you must denote it by preappending the variable name with #.
In contrast, client_1 is a local variable, which exists only within a single method or block. In your snippet, you have assigned a value to the client_1 local variable, but not to the#client_1 instance variable, which is nil until assigned.