def test_delete_reattach():
"""Removing the root from a 2-depth V should reattach nodes correctly."""
tree = AVLTree([3, 2, 4, 1, 5])
tree.delete(3)
assert 3 not in tree
assert pre_order(tree) == [2, 1, 4, 5]
assert_avl_invariants(tree.root)
def test_delete_trivial(insert, delete, expected):
"""Tests deletion of root/leaf nodes requiring no rotation."""
tree = AVLTree(insert)
tree.delete(delete)
assert delete not in tree
assert pre_order(tree) == expected
assert_avl_invariants(tree.root)
def test_delete_single_rotation(insert, delete, expected):
"""Tests deletion resulting in a single rotation."""
tree = AVLTree(insert)
tree.delete(delete)
assert delete not in tree
assert pre_order(tree) == expected
assert_avl_invariants(tree.root)
def test_delete_attach_without_rotation(insert, deletes, expected):
"""Tests selective pruning of nodes and reattaching them to parents."""
tree = AVLTree(insert)
for key in deletes:
tree.delete(key)
assert key not in tree
assert pre_order(tree) == expected
assert_avl_invariants(tree.root)
def test_delete_rotation_under_root(insert, delete):
tree = AVLTree(insert)
tree.delete(delete)
assert delete not in tree
expected = sorted(insert)
expected.remove(delete)
assert in_order(tree) == expected
assert_avl_invariants(tree.root)
def test_delete_double_rotation():
"""Tests deletion resulting in a double rotation."""
tree = AVLTree([16, 8, 24, 4, 12, 20, 28, 2, 6, 10, 32, 1, 3])
tree.delete(20)
assert 20 not in tree
assert tree.root.value == 8
assert tree.root.left.value == 4
assert tree.root.right.value == 16
assert_avl_invariants(tree.root)
def test_two_way_rotations_with_subtree_at_pivot(insert, delete):
"""Deletion causes a LR or RL rotation and the new subtree root has children."""
tree = AVLTree(insert)
tree.delete(delete)
assert delete not in tree
expected = sorted(insert)
expected.remove(delete)
assert in_order(tree) == expected
assert_avl_invariants(tree.root)
def test_double_insert_exception():
tree = AVLTree([5])
with pytest.raises(ValueError):
tree.insert(5)
def test_instantiate_from_string():
tree = AVLTree("abc")
assert "a" in tree
assert "b" in tree
assert "c" in tree
def test_instantiate_from_iter():
tree = AVLTree(range(1, 3))
assert 1 in tree
assert 2 in tree
def test_instantiate_from_list():
tree = AVLTree([1, 2])
assert 1 in tree
assert 2 in tree
def test_tree_insert():
tree = AVLTree()
tree.insert(5)
assert 5 in tree
def test_rank_ordered_traversal(rank_order):
tree = AVLTree(rank_order)
assert list(breadth_first(tree)) == rank_order
def test_empty_tree_traversal(traverser):
assert list(traverser(AVLTree())) == []
def test_basic_rotations(insert, expected):
"""Tests basic tree rotations and resulting balance."""
tree = AVLTree(insert)
assert_avl_invariants(tree.root)
assert pre_order(tree) == expected
def test_delete_nonexisting():
"""Tests deletion of nonexisting key raises KeyError."""
tree = AVLTree()
with pytest.raises(KeyError):
tree.delete(2)
def test_delete_root():
"""Tests deletion of singular root node."""
tree = AVLTree([1])
tree.delete(1)
assert 1 not in tree
assert tree.root is None
def test_double_rotation():
tree = AVLTree([5, 4, 3, 2, 1])
assert_avl_invariants(tree.root)
assert pre_order(tree) == [4, 2, 1, 3, 5]
@pytest.fixture(params=[depth_first_inorder, ordered_iterative])
def in_order_traverser(request):
"""Returns an in-order traverser."""
return request.param
@pytest.mark.parametrize(
"traverser", [breadth_first, depth_first_inorder, ordered_iterative])
def test_empty_tree_traversal(traverser):
assert list(traverser(AVLTree())) == []
@pytest.mark.parametrize(
"tree, expected",
[
(AVLTree([4, 2, 6, 1, 3, 5, 7]), [1, 2, 3, 4, 5, 6, 7]),
(AVLTree([4, 2, 6, 1, 5, 7]), [1, 2, 4, 5, 6, 7]),
(AVLTree([4, 2, 6, 3, 5, 7]), [2, 3, 4, 5, 6, 7]),
(AVLTree(range(30, 100)), list(range(30, 100))),
],
)
def test_ordered_traversal(in_order_traverser, tree, expected):
assert list(in_order_traverser(tree)) == expected
@pytest.mark.parametrize(
"tree, child, expected",
[
(AVLTree([4, 2, 6, 1, 3]), "left", [1, 2, 3]),
(AVLTree([4, 2, 6, 5, 7]), "right", [5, 6, 7]),
(AVLTree([4, 2, 6, 1]), "left", [1, 2]),