Fixes The Bug In Radix Tree. Issue #11316

data_structures/trie/radix_tree.py

@@ -1,3 +1,5 @@
+import unittest
+
 """
 A Radix Tree is a data structure that represents a space-optimized
 trie (prefix tree) in whicheach node that is the only child is merged
@@ -62,6 +64,11 @@ def insert(self, word: str) -> None:
         -- A   (leaf)
         --- A   (leaf)
         """
+        ## Handle the Case where word is empty by using an if branch
+        if word == "":
+            self.is_leaf = True
+            return
+
         # Case 1: If the word is the prefix of the node
         # Solution: We set the current node as leaf
         if self.prefix == word and not self.is_leaf:
@@ -191,39 +198,42 @@ def print_tree(self, height: int = 0) -> None:
             value.print_tree(height + 1)
 
 
-def test_trie() -> bool:
-    words = "banana bananas bandana band apple all beast".split()
-    root = RadixNode()
-    root.insert_many(words)
-
-    assert all(root.find(word) for word in words)
-    assert not root.find("bandanas")
-    assert not root.find("apps")
-    root.delete("all")
-    assert not root.find("all")
-    root.delete("banana")
-    assert not root.find("banana")
-    assert root.find("bananas")
+## write unit test for the code using unittest library with
+## logic similar to test_trie() function
+## and call it from main()
 
-    return True
 
+class TestRadixNode(unittest.TestCase):
+    def test_trie(self) -> None:
+        words = "banana bananas bandana band apple all beast".split()
+        root = RadixNode()
+        root.insert_many(words)
 
-def pytests() -> None:
-    assert test_trie()
+        assert all(root.find(word) for word in words)
+        assert not root.find("bandanas")
+        assert not root.find("apps")
+        root.delete("all")
+        assert not root.find("all")
+        root.delete("banana")
+        assert not root.find("banana")
+        assert root.find("bananas")
 
+    def test_trie_2(self) -> None:
+        """
+        now add a new test case which inserts
+        foobbb, fooaaa, foo in the given order and checks
+        for different assertions
+        """
+        words = "foobbb fooaaa foo".split()
+        root = RadixNode()
+        root.insert_many(words)
 
-def main() -> None:
-    """
-    >>> pytests()
-    """
-    root = RadixNode()
-    words = "banana bananas bandanas bandana band apple all beast".split()
-    root.insert_many(words)
-
-    print("Words:", words)
-    print("Tree:")
-    root.print_tree()
+        assert all(root.find(word) for word in words)
+        root.delete("foo")
+        assert not root.find("foo")
+        assert root.find("foobbb")
+        assert root.find("fooaaa")
 
 
 if __name__ == "__main__":
-    main()
+    unittest.main()