Added test cases for BST deletion #66

src/_DataStructures_/Trees/BinarySearchTree/bst-deletion.test.js

@@ -0,0 +1,51 @@
+const BinarySearchTree = require('./index');
+const heightOfBST = require('./height-of-bst/index');
+
+describe('Binary search tree traversals', () => {
+  let bst;
+
+  describe('Creates BST', () => {
+    it('should create BST', () => {
+      // Creates BST
+      bst = new BinarySearchTree(6);
+      bst.add(4);
+      bst.add(9);
+      bst.add(2);
+      bst.add(5);
+      bst.add(8);
+      bst.add(12);
+    });
+  });
+
+  describe('Check bst was created as expected', () => {
+    it('Inorder traversal of the created bst should be [ 2, 4, 5, 6, 8, 9, 12 ]', () => {
+      expect(bst.traverseInorder()).toEqual([2, 4, 5, 6, 8, 9, 12]);
+    });
+
+    it('Preorder traversal of the created bst should be [ 6, 4, 2, 5, 9, 8, 12 ]', () => {
+      expect(bst.traversePreorder()).toEqual([6, 4, 2, 5, 9, 8, 12]);
+    });
+
+    it('Postorder traversal of the created bst should be  [ 2, 5, 4, 8, 12, 9, 6 ]', () => {
+      expect(bst.traversePostorder()).toEqual([2, 5, 4, 8, 12, 9, 6]);
+    });
+  });
+
+  describe('BST node deletions', () => {
+    it('should check height of bst to be 3 prior deletion', () => {
+      expect(heightOfBST(bst.root)).toEqual(3);
+    });
+
+    it('deleting leaf element does not affect tree height if it has sibling', () => {
+      bst.remove(2);
+      bst.remove(8);
+      expect(heightOfBST(bst.root)).toEqual(3);
+    });
+
+    it('deleting leaf element does affect tree height if it has no-sibling', () => {
+      bst.remove(5);
+      bst.remove(12);
+      expect(heightOfBST(bst.root)).toEqual(2);
+    });
+  });
+});