def test_make_position_returns_None_with_sentinel_node_parameter(self):
pl = PositionalList()
header_node = pl._header
trailer_node = pl._trailer
result_header = pl._make_position(header_node)
result_trailer = pl._make_position(trailer_node)
self.assertIsNone(result_header)
self.assertIsNone(result_trailer)
def test_make_position_returns_Position_instance_for_given_node(self):
pl = PositionalList()
n = PositionalList._Node('foo', pl._header, pl._trailer)
pl._header._next = n
pl._trailer._prev = n
expected_position = PositionalList.Position(pl, n)
result_position = pl._make_position(n)
# comparing the instances done using the Position's __eq__ method
self.assertEqual(result_position, expected_position)