Some test cases for a TCP chat server

chat_server_test.rb

require 'open3'

IP_ADDRESS = '192.168.1.103'
PORT = 1337
WELCOME_MSG_LENGTH = 'Welcome to chat server'.length + 1
TEST_MSG = 'hello'
RECVD_MSG = 'Message Sent'

def assert(thing,msg)
  unless thing
    raise "DANG! This didn't happen - #{msg}"
  end
end

cmd = "nc #{IP_ADDRESS} #{PORT}"
sally_input, sally_output, _, sally_thread = Open3.popen3(cmd)
alice_input, alice_output, _, alice_thread = Open3.popen3(cmd)
david_input, david_output, _, david_thread = Open3.popen3(cmd)

# pull the welcome message out of each pipe
[sally_output,alice_output,david_output].each{ |f| f.read(WELCOME_MSG_LENGTH) }

unless sally_thread.status == "sleep"
  raise "Connect failed. Check the server is listening #{IP_ADDRESS}:#{PORT}"
end

# send a message, check that is received only by the others
sally_input.write(TEST_MSG)
assert(sally_output.read(RECVD_MSG.length) == RECVD_MSG, 'sally did not got the message')
assert(david_output.read(TEST_MSG.length) == TEST_MSG, 'david got the message')
assert(alice_output.read(TEST_MSG.length) == TEST_MSG, 'alice got the message')
sally_output.read(1)

david_input.write(TEST_MSG)
assert(david_output.read(RECVD_MSG.length) == RECVD_MSG, 'david did not got the message')
assert(sally_output.read(TEST_MSG.length) == TEST_MSG, 'sally got the message')
assert(alice_output.read(TEST_MSG.length) == TEST_MSG, 'alice got the message')
david_output.read(1)

alice_input.write(TEST_MSG)
assert(alice_output.read(RECVD_MSG.length) == RECVD_MSG, 'alice did not got the message')
assert(david_output.read(TEST_MSG.length) == TEST_MSG, 'david got the message')
assert(sally_output.read(TEST_MSG.length) == TEST_MSG, 'sally got the message')
alice_output.read(1)

sally_thread.kill
alice_input.write(TEST_MSG)
assert(alice_output.read(RECVD_MSG.length) == RECVD_MSG, 'alice did not got the message')
assert(david_output.read(TEST_MSG.length) == TEST_MSG, 'david got the message')
alice_output.read(1)

david_thread.kill
alice_input.write(TEST_MSG)
assert(alice_output.read(RECVD_MSG.length) == RECVD_MSG, 'alice did not got the message')
alice_output.read(1)

mary_input, mary_output, _, mary_thread = Open3.popen3(cmd)
mary_output.read(WELCOME_MSG_LENGTH)

mary_input.write(TEST_MSG)
assert(mary_output.read(RECVD_MSG.length) == RECVD_MSG, 'mary did not got the message')
assert(alice_output.read(TEST_MSG.length) == TEST_MSG, 'alice got the message')
mary_output.read(1)

alice_input.write(TEST_MSG)
assert(alice_output.read(RECVD_MSG.length) == RECVD_MSG, 'alice did not got the message')
assert(mary_output.read(TEST_MSG.length) == TEST_MSG, 'mary got the message')
alice_output.read(1)

john_input, john_output, _, john_thread = Open3.popen3(cmd)
john_output.read(WELCOME_MSG_LENGTH)

alice_input.write(TEST_MSG)
assert(alice_output.read(RECVD_MSG.length) == RECVD_MSG, 'alice did not got the message')
assert(mary_output.read(TEST_MSG.length) == TEST_MSG, 'mary got the message')
assert(john_output.read(TEST_MSG.length) == TEST_MSG, 'john got the message')
alice_output.read(1)

alice_thread.kill

john_input.write(TEST_MSG)
assert(john_output.read(RECVD_MSG.length) == RECVD_MSG, 'john did not got the message')
assert(mary_output.read(TEST_MSG.length) == TEST_MSG, 'mary got the message')
john_output.read(1)

[john_thread,mary_thread].each(&:kill)

puts 'tests passed'