implement stack

Author: amejiarosario

src/stacks-and-queues/stack.js

@@ -0,0 +1,17 @@
+const LinkedList = require('../linked-list/linkedlist');
+
+class Stack {
+  constructor() {
+    this.list = new LinkedList();
+  }
+
+  push(data) {
+    this.list.addLast(data);
+  }
+
+  pop() {
+    return this.list.removeLast();
+  }
+}
+
+module.exports = Stack;

src/stacks-and-queues/stack.spec.js

@@ -0,0 +1,29 @@
+const expect = require('chai').expect;
+const Stack = require('./stack');
+
+describe('Stacks: QueueViaStack', function () {
+  let stack;
+
+  beforeEach(function () {
+    stack = new Stack();
+  });
+
+  describe('.add', function () {
+    it('should hold an element', function () {
+      stack.push(1);
+      expect(stack.list.head.data).to.equal(1);
+    });
+  });
+
+  describe('.remove', function () {
+    it('should handle removing from empty stack', function () {
+      expect(stack.pop()).to.equal(undefined);
+    });
+
+    it('should remove an element', function () {
+      stack.push(1);
+      expect(stack.pop()).to.equal(1);
+    });
+  });
+
+});