new_contents: import unittest
  from game.world import World
  from game.player import Player
  
  class TestWorld(unittest.TestCase):
  	
  	def setUp(self):
  		self.world = World()
  
  	def test_add_player(self):
  		player = Player()
  		self.world.add_player(player)
  		assertTrue(player in self.world.players)
  
subject: Create testworld.py