def test_cell_with_four_neighbors_dies():
cell = (4,5)
crowded_world = set([cell, (3,5), (4,4), (5,5), (3,4)])
assert g.cell_survives(crowded_world, cell) is False
def test_cell_with_three_neighbors_survives():
cell = (4,5)
comfortable_world = set([cell, (3,5), (4,4), (5,5)])
assert g.cell_survives(comfortable_world, cell) is True
def test_cell_with_no_neighbors_dies():
cell = (4,5)
lonely_world = set([cell])
assert g.cell_survives(lonely_world, cell) is False