Add validate_bst function for testing purposes

algorithms/tree/bst/bst.py

@@ -6,7 +6,7 @@
     4. Traversal (Preorder, Inorder, Postorder)
 """
 
-import unittest
+import math
 
 class Node(object):
     def __init__(self, data):
@@ -99,41 +99,20 @@ def postorder(self, root):
             self.postorder(root.right)
             print(str(root.data), end = ' ')
 
-"""
-    The tree is created for testing:
-
-                    10
-                 /      \
-               6         15
-              / \       /   \
-            4     9   12      24
-                 /          /    \
-                7         20      30
-                         /
-                       18
-"""
-
-class TestSuite(unittest.TestCase):
-    def setUp(self):
-        self.tree = BST()
-        self.tree.insert(10)
-        self.tree.insert(15)
-        self.tree.insert(6)
-        self.tree.insert(4)
-        self.tree.insert(9)
-        self.tree.insert(12)
-        self.tree.insert(24)
-        self.tree.insert(7)
-        self.tree.insert(20)
-        self.tree.insert(30)
-        self.tree.insert(18)
+    def validate_bst(self):
+        """ Visits node through inorder dfs, and validates that the tree is a BST
+        :rtype: bool
+        """
+        def in_order(root, prev):
 
-    def test_search(self):
-        self.assertTrue(self.tree.search(24))
-        self.assertFalse(self.tree.search(50))
-
-    def test_size(self):
-        self.assertEqual(11, self.tree.size())
-
-if __name__ == '__main__':
-    unittest.main()
+            if root == None:
+                return True
+            if not in_order(root.left, prev):
+                return False
+            if root.data <= prev:
+                return False
+            prev = root.data
+            return in_order(root.right, prev)
+
+        prev = -math.inf
+        return in_order(self.root, prev)

tests/test_tree.py

@@ -1,3 +1,4 @@
+from algorithms.tree.bst.bst import BST
 from algorithms.tree.traversal import (
     preorder,
     preorder_rec,
@@ -7,11 +8,8 @@
     inorder_rec
 )
 from algorithms.tree.b_tree import BTree
-
 from algorithms.tree import construct_tree_postorder_preorder as ctpp
-
 from algorithms.tree.fenwick_tree.fenwick_tree import Fenwick_Tree
-
 import unittest
 
 
@@ -175,6 +173,61 @@ def test_construct_tree_with_update_3(self):
         ft.update_bit(bit_tree, 2, 11)
         self.assertEqual(23, ft.get_sum(bit_tree, 4))
 
+class TestBST(unittest.TestCase):
+    """
+    Testing binary search tree functionality
+    """
+
+    def test_insert(self):
+        """
+        Testing that bst structure is valid after insert
+        """
+        bst = create_bst()
+        self.assertTrue(bst.validate_bst())
+
+    def test_search(self):
+        """
+        Testing search functionality
+        """
+        bst = create_bst()
+        self.assertTrue(bst.search(24))
+        self.assertFalse(bst.search(50))
+
+    def test_size(self):
+        """
+        Testing size function
+        """
+        bst = create_bst()
+        self.assertEqual(11, bst.size())
+
+
+def create_bst():
+    """
+    The following tree is created for testing:
+
+                    10
+                 /      \
+               6         15
+              / \       /   \
+            4     9   12      24
+                 /          /    \
+                7         20      30
+                         /
+                       18
+    """
+    tree = BST()
+    tree.insert(10)
+    tree.insert(15)
+    tree.insert(6)
+    tree.insert(4)
+    tree.insert(9)
+    tree.insert(12)
+    tree.insert(24)
+    tree.insert(7)
+    tree.insert(20)
+    tree.insert(30)
+    tree.insert(18)
+    return tree
 
 if __name__ == '__main__':
     unittest.main()