def test_linked_list_can_set_and_get_head():
node1 = LinkedListNode(1, None, None)
node2 = LinkedListNode(2, None, node1)
node1.set_next(node2)
linked_list = LinkedList()
linked_list.set_head(node1)
assert linked_list.get_head() == node1
def test_linked_list_find_returns_index_when_value_is_present():
node1 = LinkedListNode(1, None, None)
node2 = LinkedListNode(4, None, node1)
node1.set_next(node2)
linked_list = LinkedList()
linked_list.set_head(node1)
result = linked_list.find(4)
assert result == 1
def test_linked_list_find_returns_minus_one_when_absent():
node1 = LinkedListNode(1, None, None)
node2 = LinkedListNode(2, None, node1)
node1.set_next(node2)
linked_list = LinkedList()
linked_list.set_head(node1)
result = linked_list.find(3)
assert result == -1
def test_linked_list_insert_adds_node_to_front_with_index_zero():
node1 = LinkedListNode(2, None, None)
node2 = LinkedListNode(4, None, node1)
node1.set_next(node2)
linked_list = LinkedList()
linked_list.set_head(node1)
new_node = LinkedListNode(1, None, None)
linked_list.insert(0, new_node)
assert linked_list.get_head() == new_node
assert linked_list.get_head().get_next() == node1
assert node1.get_previous() == new_node
def test_linked_list_delete_removes_head_with_index_zero():
node1 = LinkedListNode(1, None, None)
node2 = LinkedListNode(4, None, node1)
node1.set_next(node2)
linked_list = LinkedList()
linked_list.set_head(node1)
linked_list.delete(0)
assert linked_list.get_head() == node2
assert node2.get_previous() == None
def test_linked_list_delete_raises_exception_when_index_too_high():
node1 = LinkedListNode(1, None, None)
node2 = LinkedListNode(4, None, node1)
node1.set_next(node2)
linked_list = LinkedList()
linked_list.set_head(node1)
with pytest.raises(Exception):
linked_list.delete(4)
def test_linked_list_insert_adds_node_at_appropriate_index():
node1 = LinkedListNode(2, None, None)
node2 = LinkedListNode(4, None, node1)
node1.set_next(node2)
linked_list = LinkedList()
linked_list.set_head(node1)
new_node = LinkedListNode(3, None, None)
linked_list.insert(1, new_node)
assert linked_list.get_head().get_next() == new_node
assert new_node.get_previous() == node1
assert node2.get_previous() == new_node
assert new_node.get_next() == node2
def test_linked_list_insert_raises_exception_when_index_too_high():
node1 = LinkedListNode(1, None, None)
node2 = LinkedListNode(4, None, node1)
node1.set_next(node2)
linked_list = LinkedList()
linked_list.set_head(node1)
new_node = LinkedListNode(6, None, None)
with pytest.raises(Exception):
linked_list.insert(4, new_node)
def test_linked_list_delete_removes_node_at_end_of_list():
node1 = LinkedListNode(1, None, None)
node2 = LinkedListNode(4, None, node1)
node3 = LinkedListNode(5, None, node2)
node1.set_next(node2)
node2.set_next(node3)
linked_list = LinkedList()
linked_list.set_head(node1)
linked_list.delete(2)
assert node2.get_next() is None
def test_linked_list_insert_adds_node_at_last_index():
node1 = LinkedListNode(2, None, None)
node2 = LinkedListNode(4, None, node1)
node1.set_next(node2)
linked_list = LinkedList()
linked_list.set_head(node1)
new_node = LinkedListNode(5, None, None)
linked_list.insert(2, new_node)
assert new_node.get_previous() == node2
assert node2.get_next() == new_node
assert new_node.get_next() == None
def test_linked_list_delete_removes_node_with_given_index():
node1 = LinkedListNode(1, None, None)
node2 = LinkedListNode(4, None, node1)
node3 = LinkedListNode(5, None, node2)
node1.set_next(node2)
node2.set_next(node3)
linked_list = LinkedList()
linked_list.set_head(node1)
linked_list.delete(1)
assert node1.get_next() == node3
assert node3.get_previous() == node1
def test_linked_list_can_be_created_with_proper_parameters():
result = LinkedList()
assert result.get_head() is None