Test that it is possible to use objects and binary tree node values.

src/data-structures/tree/__test__/BinaryTreeNode.test.js

@@ -173,4 +173,27 @@ describe('BinaryTreeNode', () => {
     expect(root.left).toBeNull();
     expect(root.right).toBeNull();
   });
+
+  it('should be possible to create node with object as a value', () => {
+    const obj1 = { key: 'object_1', toString: () => 'object_1' };
+    const obj2 = { key: 'object_2' };
+
+    const node1 = new BinaryTreeNode(obj1);
+    const node2 = new BinaryTreeNode(obj2);
+
+    node1.setLeft(node2);
+
+    expect(node1.value).toEqual(obj1);
+    expect(node2.value).toEqual(obj2);
+    expect(node1.left.value).toEqual(obj2);
+
+    node1.removeChild(node2);
+
+    expect(node1.value).toEqual(obj1);
+    expect(node2.value).toEqual(obj2);
+    expect(node1.left).toBeNull();
+
+    expect(node1.toString()).toBe('object_1');
+    expect(node2.toString()).toBe('[object Object]');
+  });
 });