def test_first_1(self):
"""get first elt from empty list -> None"""
expected = "a"
pl = PositionalList()
pl.add_first('a')
res = pl.first()
self.assertIsInstance(res, PositionalList.Position)
actual = res.payload()
self.assertEqual(actual, expected)
def test_first_3(self):
expected = "c"
pl = PositionalList()
pl.add_first('a')
pl.add_first('b')
pl.add_first('c')
res = pl.first()
self.assertIsInstance(res, PositionalList.Position)
actual = res.payload()
self.assertEqual(actual, expected)
def test_delete_len(self):
pl = PositionalList()
a = pl.add_first('a')
b = pl.add_after(a, 'b')
c = pl.add_last('c')
d = pl.add_after(c, 'd')
self.assertEqual(len(pl), 4)
pl.delete(a)
self.assertEqual(len(pl), 3)
pl.delete(pl.first())
self.assertEqual(len(pl), 2)
pl.delete(pl.last())
self.assertEqual(len(pl), 1)
self.assertTrue(pl)
pl.delete(c)
self.assertEqual(len(pl), 0)
self.assertFalse(pl)
def test_last_first_0(self):
expected_first = "a"
expected_last = "z"
pl = PositionalList()
pl.add_first('c')
pl.add_last('x')
pl.add_first('b')
pl.add_last('y')
pl.add_last('z')
pl.add_first('a')
res = pl.first()
self.assertIsInstance(res, PositionalList.Position)
actual_first = res.payload()
self.assertEqual(actual_first, expected_first)
res = pl.last()
self.assertIsInstance(res, PositionalList.Position)
actual_last = res.payload()
self.assertEqual(actual_last, expected_last)
self.assertEqual(len(pl), 6)
def test_first_0(self):
"""get first elt from empty list -> None"""
pl = PositionalList()
actual = pl.first()
self.assertIsNone(actual)