def test_remove_front_back():
dllist = DLList()
dllist.add(0, 100)
dllist.remove(0) == 100
dllist.remove(1) == None
dllist.add(0, 200)
dllist.add(1, 150)
dllist.add(2, 300)
assert dllist.remove(0) == 200
x = dllist.dummy.front.front
assert x.back.data == 150
assert x.data == 300
def test_remove():
dllist= DLList()
assert dllist.remove(0) == None
dllist.add(0, 10)
dllist.add(1, 20)
dllist.add(2, 100)
dllist.add(3, 40)
assert dllist.remove(1) ==20
assert dllist.size == 3
assert dllist.dummy.front.data == 10
assert dllist.remove(0) ==10
assert dllist.dummy.front.data == 100
assert dllist.size == 2
assert dllist.remove(1) ==40
assert dllist.dummy.back.data == 100
assert dllist.size == 1
def test_remove_head_tail():
dllist = DLList()
dllist.add(0, 10)
dllist.add(1, 20)
dllist.add(2, 100)
dllist.add(3, 40)
assert dllist.remove(0) == 10
assert dllist.dummy.front.data == 20
assert dllist.dummy.back.data == 40
assert dllist.size == 3
assert dllist.get(0) == 20
assert dllist.get(1) == 100