Reworked notebook: Added more detail to constraints and test cases. Reworked unit test. Added linebreak to comment about naming clash with queue.

stacks-queues/queue-list.ipynb

@@ -13,10 +13,11 @@
    "source": [
     "## Problem: Implement a queue with enqueue and dequeue methods using a linked list.\n",
     "\n",
-    "* [Clarifying Questions](#Clarifying-Questions)\n",
+    "* [Constraints and Assumptions](#Constraints-and-Assumptions)\n",
     "* [Test Cases](#Test-Cases)\n",
     "* [Algorithm](#Algorithm)\n",
     "* [Code](#Code)\n",
+    "* [Unit Test](#Unit-Test)\n",
     "* [Pythonic-Code](#Pythonic-Code)"
    ]
   },
@@ -24,7 +25,9 @@
    "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",
     "* If there is one item in the list, do you expect the first and last pointers to both point to it?\n",
     "    * Yes\n",
@@ -91,14 +94,23 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 1,
    "metadata": {
     "collapsed": false
    },
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Overwriting queue_list.py\n"
+     ]
+    }
+   ],
    "source": [
     "%%writefile queue_list.py\n",
-    "# Need to avoid naming this queue.py as it will conflict with IPython Notebook\n",
+    "# Need to avoid naming this queue.py as it \n",
+    "# will conflict with IPython Notebook\n",
     "\n",
     "class Node(object):\n",
     "    def __init__(self, data):\n",
@@ -123,6 +135,7 @@
     "        # Empty list\n",
     "        if self.first is None and self.last is None:\n",
     "            return None\n",
+    "        \n",
     "        # Remove only element from a one element list\n",
     "        elif self.first == self.last:\n",
     "            data = self.first.data\n",
@@ -137,7 +150,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 2,
    "metadata": {
     "collapsed": false
    },
@@ -146,29 +159,67 @@
     "%run queue_list.py"
    ]
   },
+  {
+   "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 an empty queue\n",
+      "Test: Enqueue to an empty queue\n",
+      "Test: Dequeue a queue with one element\n",
+      "Test: Enqueue to a non-empty queue\n",
+      "Test: Dequeue a queue with more than one element\n",
+      "Success: test_end_to_end\n"
+     ]
+    }
+   ],
    "source": [
-    "print('Dequeue an empty queue')\n",
-    "queue = Queue()\n",
-    "print(queue.dequeue())\n",
-    "print('Enqueue to an empty queue')\n",
-    "queue.enqueue(1)\n",
-    "print('Dequeue a queue with one element')\n",
-    "print(queue.dequeue())\n",
-    "print('Enqueue to a non-empty queue')\n",
-    "queue.enqueue(2)\n",
-    "queue.enqueue(3)\n",
-    "queue.enqueue(4)\n",
-    "print('Dequeue a queue with more than one element')\n",
-    "print(queue.dequeue())\n",
-    "print(queue.dequeue())\n",
-    "print(queue.dequeue())"
+    "from nose.tools import assert_equal\n",
+    "\n",
+    "class Test(object):\n",
+    "    # TODO: It would be better if we had unit tests for each\n",
+    "    # method in addition to the following end-to-end test\n",
+    "    def test_end_to_end(self):\n",
+    "        print('Test: Dequeue an empty queue')\n",
+    "        queue = Queue()\n",
+    "        assert_equal(queue.dequeue(), None)\n",
+    "\n",
+    "        print('Test: Enqueue to an empty queue')\n",
+    "        queue.enqueue(1)\n",
+    "\n",
+    "        print('Test: Dequeue a queue with one element')\n",
+    "        assert_equal(queue.dequeue(), 1)\n",
+    "\n",
+    "        print('Test: Enqueue to a non-empty queue')\n",
+    "        queue.enqueue(2)\n",
+    "        queue.enqueue(3)\n",
+    "        queue.enqueue(4)\n",
+    "\n",
+    "        print('Test: Dequeue a queue with more than one element')\n",
+    "        assert_equal(queue.dequeue(), 2)\n",
+    "        assert_equal(queue.dequeue(), 3)\n",
+    "        assert_equal(queue.dequeue(), 4)\n",
+    "        \n",
+    "        print('Success: test_end_to_end')\n",
+    "\n",
+    "if __name__ == '__main__':\n",
+    "    test = Test()\n",
+    "    test.test_end_to_end()"
    ]
   },
   {

stacks-queues/queue_list.py

@@ -1,4 +1,5 @@
-# Need to avoid naming this queue.py as it will conflict with IPython Notebook
+# Need to avoid naming this queue.py as it 
+# will conflict with IPython Notebook
 
 class Node(object):
     def __init__(self, data):