Added tests for BST insertion

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

@@ -0,0 +1,51 @@
+const BinarySearchTree = require('./index');
+
+describe('Binary Search Tree', () => {
+  let bst;
+  let rootsLeftChild, rootsRightChild;
+  let rootsLeftChildsLeftChild, rootsLeftChildsRightChild;
+  let rootsRightChildsLeftChild, rootsRightChildsRightChild;
+
+  describe('Creates a binary search tree', () => {
+    it('should create a bst with root 100', () => {
+      bst = new BinarySearchTree(100);
+      expect(bst.root.value).toEqual(100);
+    });
+
+    it('should add element 20 to the left of root node', () => {
+      bst.add(20);
+      rootsLeftChild = bst.root.leftChild;
+      expect(rootsLeftChild.value).toEqual(20);
+    });
+
+    it('should add element 500 to the right of root node', () => {
+      bst.add(500);
+      rootsRightChild = bst.root.rightChild;
+      expect(rootsRightChild.value).toEqual(500);
+    });
+
+    it('should add element 10 to the left of root"s left child', () => {
+      bst.add(10);
+      rootsLeftChildsLeftChild = bst.root.leftChild.leftChild;
+      expect(rootsLeftChildsLeftChild.value).toEqual(10);
+    });
+
+    it('should add element 30 to the right of root"s left child', () => {
+      bst.add(30);
+      rootsLeftChildsRightChild = bst.root.leftChild.rightChild;
+      expect(rootsLeftChildsRightChild.value).toEqual(30);
+    });
+
+    it('should add element 400 to the left of root"s right child', () => {
+      bst.add(400);
+      rootsRightChildsLeftChild = bst.root.rightChild.leftChild;
+      expect(rootsRightChildsLeftChild.value).toEqual(400);
+    });
+
+    it('should add element 600 to the right of root"s right child', () => {
+      bst.add(600);
+      rootsRightChildsRightChild = bst.root.rightChild.rightChild;
+      expect(rootsRightChildsRightChild.value).toEqual(600);
+    });
+  });
+});