def test_fuzz(self):
"""Perform some basic randomized input testing."""
repeat_times = 5
sample_set = range(-1000, 1001)
bst = BinarySearchTree()
for i in range(repeat_times):
# Insert elements
for j in random.sample(sample_set, len(sample_set)):
bst.insert(j)
# Search for elements
for j in random.sample(sample_set, len(sample_set)):
self.assertEqual(j, bst.search(j))
# Delete elements
for j in random.sample(sample_set, len(sample_set)):
self.assertTrue(bst.delete(j))
self.assertIsNone(bst.search(j))
def test_basic_checks(self):
bst = BinarySearchTree()
# Root node: 7
bst.insert(7)
self.assertEqual(7, bst.root.key, "Insert key as root")
# 7
# /
# 3
bst.insert(3)
self.assertEqual(3, bst.root.left.key, "Insert key as root's left child")
# 7
# / \
# 3 11
bst.insert(11)
self.assertEqual(11, bst.root.right.key, "Insert key as root's right child")
# 7
# / \
# 3 11
# /
# 1
bst.insert(1)
self.assertEqual(1, bst.root.left.left.key, "Insert key as left child of non-root node")
# 7
# / \
# 3 11
# / \
# 1 13
bst.insert(13)
self.assertEqual(13, bst.root.right.right.key, "Insert key as right child of non-root node")
# 7
# / \
# 3 11
# / / \
# 1 9 13
bst.insert(9)
self.assertEqual(9, bst.root.right.left.key, "Insert key as left child of right child")
# 7
# / \
# 3 11
# / \ / \
# 1 5 9 13
bst.insert(5)
self.assertEqual(5, bst.root.left.right.key, "Insert key as right child of left child")
for i in range(1, 14, 2):
self.assertEqual(i, bst.search(i), "Search full tree for {}.".format(i))
for i in range(0, 15, 2):
self.assertIsNone(bst.search(i), "Search full tree for nonexistent items.")
# By adding a few more elements, we can test all basic deletion cases with a bit of planning.
# (Some corner cases may not be covered, e.g. testing whether a replacement works with both None and Node)
# 7
# / \
# 3 11
# / \ / \
# 1 5 9 13
# / /
# 8 12
bst.insert(8)
bst.insert(12)
# Possible deletion cases:
# A - delete root with successor as leftmost child of right subtree (IOS)
# B - delete root with left and right children, right has no left subtree
# C - delete root with only right child
# D - delete root with only left child
# E - delete root with no children, leaving an empty tree
# F - delete non-root node with successor as leftmost child of right subtree (IOS)
# G - delete non-root node with only right child
# H - delete non-root node with only left child
# I - delete non-root node with left and right children, right child is a leaf
# J - delete non-root leaf
# Deletions, in order, matched with cases above:
# 7 - A
# 3 - I
# 11 - F
# 9 - J
# 5 - H
# 12 - G
# 8 - B
# 13 - D
# This leaves a tree with one node, 1.
# Then we'll insert 2 to form the tree
# 1
# \
# 2
# And we'll delete:
# 1 - C
# 2 - E
for i in [7, 3, 11, 9, 5, 12, 8, 13]:
self.assertTrue(bst.delete(i), "Test deletion cases")
self.assertIsNone(bst.search(i), "Search for deleted item")
bst.insert(2)
for i in [1, 2]:
self.assertTrue(bst.delete(i), "Test deletion cases")
self.assertIsNone(bst.search(i), "Search for deleted item")
self.assertFalse(bst.delete(6), "Delete item that's not in the tree")
self.assertFalse(bst.delete(7), "Delete item previously removed from tree")
self.assertIsNone(bst.search(1), "Search empty tree")
