main.py

from random import randint


LIVING_SPACE_CELL_SIZE = 24


class Alive(object):
    pass


class Dead(object):
    pass


def get_next_state(position, current_generation):
    """
    :param list combo: 3 objects that are either Dead or Alive
    
    :return: if a middle cell should live or not based on neighbours
    :rtype: object (either Dead or Alive)
    
    Outcomes:
    
    111 Dead
    110 Dead
    101 Dead
    100 Alive 
    011 Alive
    011 Dead
    010 Dead
    001 Dead
    000 Dead
    """
    # Edge case 1 (left side)
    if position < 1:
        combo = [ 
                type(current_generation[len(current_generation) - 1]),
                type(current_generation[position]),
                type(current_generation[position + 1])  
        ]
    # Edge case 2 (right side)
    elif position == len(current_generation) - 1:
        combo = [
                type(current_generation[position - 1]),
                type(current_generation[position]),
                type(current_generation[0])  
        ]
    else:
        combo = [
                type(current_generation[position - 1]),
                type(current_generation[position]),
                type(current_generation[position + 1])  
        ]
    print 'combo', combo    
    should_live = False
    
    if combo == [type(Alive), type(Dead), type(Dead)]:
        should_live = True
        
    if combo == [type(Dead), type(Alive), type(Alive)]:
        should_live = True
        
    return Alive() if should_live else Dead()


if __name__ == "__main__":
    current_generation = [Dead() if randint(0, 1) else Alive()
                            for _ in range(0, LIVING_SPACE_CELL_SIZE)]
    next_generation = [get_next_state(position, current_generation)
                       for position, value in enumerate(current_generation)]

output.sh

$ nose2 test
combo [<class 'main.Alive'>, <class 'main.Alive'>, <class 'main.Alive'>]
combo [<class 'main.Alive'>, <class 'main.Alive'>, <class 'main.Dead'>]
combo [<class 'main.Alive'>, <class 'main.Dead'>, <class 'main.Alive'>]
combo [<class 'main.Alive'>, <class 'main.Dead'>, <class 'main.Dead'>]
F
======================================================================
FAIL: test_get_next_state (test.TestCases)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/mark/testing/test.py", line 28, in test_get_next_state
    self.assertEqual(type(next_state), type(expected_state), '%s should be %s instead of %s' % (combo, type(expected_state), type(next_state)))
AssertionError: [<main.Alive object at 0x7f5a9df00450>, <main.Dead object at 0x7f5a9df002d0>, <main.Dead object at 0x7f5a9df00290>] should be <class 'main.Alive'> instead of <class 'main.Dead'>

----------------------------------------------------------------------
Ran 1 test in 0.001s

FAILED (failures=1)

test.py

import unittest

from main import Alive, Dead, get_next_state


class TestCases(unittest.TestCase):
        
    def test_get_next_state(self):
        outcomes = """
        111 Dead
        110 Dead
        101 Dead
        100 Alive 
        011 Alive
        011 Dead
        010 Dead
        001 Dead
        000 Dead
        """.strip()
        
        for combo, state in [outcome.strip().split(' ')
                             for outcome in outcomes.split('\n')]:
            expected_state = Alive() if state == 'Alive' else Dead()
            combo = [Dead() if val == '0' else Alive()
                     for val in combo]
            
            next_state = get_next_state(1, combo)
            self.assertEqual(type(next_state),
                             type(expected_state),
                             '%s should be %s instead of %s' % (combo,
                                                                type(expected_state),
                                                                type(next_state)))