From d6a8ff37e17253f0195cc67561a3432fcb2cd476 Mon Sep 17 00:00:00 2001
From: Donne Martin <donne.martin@gmail.com>
Date: Sat, 27 Jun 2015 06:32:43 -0400
Subject: [PATCH] Reworked notebook: Added more detail to constraints and test
 cases.  Reworked unit test.

---
 stacks-queues/queue-from-stacks.ipynb | 94 ++++++++++++++++++++-------
 1 file changed, 69 insertions(+), 25 deletions(-)

diff --git a/stacks-queues/queue-from-stacks.ipynb b/stacks-queues/queue-from-stacks.ipynb
index caddd96..cac93a9 100644
--- a/stacks-queues/queue-from-stacks.ipynb
+++ b/stacks-queues/queue-from-stacks.ipynb
@@ -13,19 +13,24 @@
    "source": [
     "## Problem: Implement a queue using two stacks.\n",
     "\n",
-    "* [Clarifying Questions](#Clarifying-Questions)\n",
+    "* [Constraints and Assumptions](#Constraints-and-Assumptions)\n",
     "* [Test Cases](#Test-Cases)\n",
     "* [Algorithm](#Algorithm)\n",
-    "* [Code](#Code)"
+    "* [Code](#Code)\n",
+    "* [Unit Test](#Unit-Test)"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "## Clarifying Questions\n",
+    "## Constraints and Assumptions\n",
+    "\n",
+    "*Problem statements are often intentionally ambiguous.  Identifying constraints and stating assumptions can help to ensure you code the intended solution.*\n",
     "\n",
     "* Do you expect the methods to be enqueue and dequeue?\n",
+    "    * Yes\n",
+    "* Can we assume we already have a stack class that can be used for this problem?\n",
     "    * Yes"
    ]
   },
@@ -92,7 +97,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 1,
    "metadata": {
     "collapsed": true
    },
@@ -103,7 +108,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 2,
    "metadata": {
     "collapsed": false
    },
@@ -129,32 +134,71 @@
     "        return self.right_stack.pop()"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Unit Test\n",
+    "\n",
+    "*It is important to identify and run through general and edge cases from the [Test Cases](#Test-Cases) section by hand.  You generally will not be asked to write a unit test like what is shown below.*"
+   ]
+  },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 3,
    "metadata": {
     "collapsed": false
    },
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Test: Dequeue on empty stack\n",
+      "Test: Enqueue on empty stack\n",
+      "Test: Enqueue on non-empty stack\n",
+      "Test: Multiple enqueue in a row\n",
+      "Test: Dequeue on non-empty stack\n",
+      "Test: Dequeue after an enqueue\n",
+      "Test: Multiple dequeue in a row\n",
+      "Test: Enqueue after a dequeue\n",
+      "Success: test_queue_from_stacks\n"
+     ]
+    }
+   ],
    "source": [
-    "print('Dequeue on empty stack')\n",
-    "queue = QueueFromStacks()\n",
-    "print(queue.dequeue())\n",
-    "print('Enqueue on empty stack')\n",
-    "print('Enqueue on non-empty stack')\n",
-    "print('Multiple enqueue in a row')\n",
-    "num_items = 3\n",
-    "for i in range (0, num_items):\n",
-    "    queue.enqueue(i)\n",
-    "print('Dequeue on non-empty stack')\n",
-    "print('Dequeue after an enqueue')\n",
-    "print(queue.dequeue())\n",
-    "print('Multiple dequeue in a row')\n",
-    "print(queue.dequeue())\n",
-    "print(queue.dequeue())\n",
-    "print('Enqueue after a dequeue')\n",
-    "queue.enqueue(5)\n",
-    "print(queue.dequeue())"
+    "from nose.tools import assert_equal\n",
+    "\n",
+    "class Test(object):\n",
+    "    def test_queue_from_stacks(self):\n",
+    "        print('Test: Dequeue on empty stack')\n",
+    "        queue = QueueFromStacks()\n",
+    "        assert_equal(queue.dequeue(), None)\n",
+    "\n",
+    "        print('Test: Enqueue on empty stack')\n",
+    "        print('Test: Enqueue on non-empty stack')\n",
+    "        print('Test: Multiple enqueue in a row')\n",
+    "        num_items = 3\n",
+    "        for i in range (0, num_items):\n",
+    "            queue.enqueue(i)\n",
+    "\n",
+    "        print('Test: Dequeue on non-empty stack')\n",
+    "        print('Test: Dequeue after an enqueue')\n",
+    "        assert_equal(queue.dequeue(), 0)\n",
+    "\n",
+    "        print('Test: Multiple dequeue in a row')\n",
+    "        assert_equal(queue.dequeue(), 1)\n",
+    "        assert_equal(queue.dequeue(), 2)\n",
+    "\n",
+    "        print('Test: Enqueue after a dequeue')\n",
+    "        queue.enqueue(5)\n",
+    "        assert_equal(queue.dequeue(), 5)\n",
+    "\n",
+    "        print('Success: test_queue_from_stacks')\n",
+    "\n",
+    "if __name__ == '__main__':\n",
+    "    test = Test()\n",
+    "    test.test_queue_from_stacks()"
    ]
   }
  ],