From 5ceedbd1e36f1caa2bced1b4103e13252ef618c9 Mon Sep 17 00:00:00 2001
From: Donne Martin <donne.martin@gmail.com>
Date: Wed, 24 Jun 2015 18:24:40 -0400
Subject: [PATCH] Reworked notebook: Added more detail to clarifying questions
 and test cases.  Reworked code and unit test.

---
 arrays-strings/reverse_string.ipynb | 85 ++++++++++++++++++-----------
 1 file changed, 54 insertions(+), 31 deletions(-)

diff --git a/arrays-strings/reverse_string.ipynb b/arrays-strings/reverse_string.ipynb
index 9cebfe7..d7d0515 100644
--- a/arrays-strings/reverse_string.ipynb
+++ b/arrays-strings/reverse_string.ipynb
@@ -18,6 +18,7 @@
     "* [Algorithm](#Algorithm)\n",
     "* [Code](#Code)\n",
     "* [Pythonic-Code](#Pythonic-Code)\n",
+    "* [Unit Test](#Unit-Test)\n",
     "* [C Algorithm](C-Algorithm)\n",
     "* [C Code]()"
    ]
@@ -28,6 +29,11 @@
    "source": [
     "## Clarifying Questions\n",
     "\n",
+    "*Problem statements are sometimes intentionally ambiguous.  Asking clarifying questions, identifying constraints, and stating assumptions help to ensure you code the intended solution.*\n",
+    "\n",
+    "* Can I assume the string is ASCII?\n",
+    "    * Yes\n",
+    "    * Note: Unicode strings could require special handling depending on your language\n",
     "* Can I use the slice operator or the reversed function?\n",
     "    * No\n",
     "* Since Python string are immutable, can I use a list instead?\n",
@@ -40,32 +46,13 @@
    "source": [
     "## Test Cases\n",
     "\n",
+    "*Identifying and running through general and edge cases are important.  You generally will not be asked to write a unit test like what is shown below.*\n",
+    "\n",
     "* NULL input\n",
     "* '' -> ''\n",
     "* 'foo bar' -> 'rab oof'"
    ]
   },
-  {
-   "cell_type": "code",
-   "execution_count": null,
-   "metadata": {
-    "collapsed": false
-   },
-   "outputs": [],
-   "source": [
-    "from nose.tools import assert_equal\n",
-    "\n",
-    "class Test(object):\n",
-    "    def test_reversed(self, func):\n",
-    "        assert_equal(func(None), None)\n",
-    "        assert_equal(func(''), '')\n",
-    "        assert_equal(func('foo bar'), 'rab oof')\n",
-    "\n",
-    "def run_tests(func):\n",
-    "    test = Test()\n",
-    "    test.test_reversed(func)"
-   ]
-  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -92,7 +79,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 1,
    "metadata": {
     "collapsed": false
    },
@@ -104,11 +91,9 @@
     "    string_list = list(string)\n",
     "    string_length = len(string_list)\n",
     "    for i in xrange(string_length/2):\n",
-    "        string_list[i], string_list[string_length - 1 - i] = \\\n",
-    "            string_list[string_length - 1 - i], string_list[i]\n",
-    "    return ''.join(string_list)\n",
-    "\n",
-    "run_tests(reverse_string)"
+    "        string_list[i], string_list[string_length-1-i] = \\\n",
+    "            string_list[string_length-1-i], string_list[i]\n",
+    "    return ''.join(string_list)"
    ]
   },
   {
@@ -122,7 +107,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 2,
    "metadata": {
     "collapsed": false
    },
@@ -136,10 +121,48 @@
     "def reverse_string_alt2(string):\n",
     "    if string is None:\n",
     "        return None    \n",
-    "    return ''.join(reversed(string))\n",
+    "    return ''.join(reversed(string))"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Unit Test"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Success: test_reversed\n",
+      "Success: test_reversed\n",
+      "Success: test_reversed\n"
+     ]
+    }
+   ],
+   "source": [
+    "from nose.tools import assert_equal\n",
     "\n",
-    "run_tests(reverse_string_alt)\n",
-    "run_tests(reverse_string_alt2)"
+    "class Test(object):\n",
+    "    def test_reversed(self, func):\n",
+    "        assert_equal(func(None), None)\n",
+    "        assert_equal(func(''), '')\n",
+    "        assert_equal(func('foo bar'), 'rab oof')\n",
+    "        print('Success: test_reversed')\n",
+    "\n",
+    "if __name__ == '__main__':\n",
+    "    test = Test()\n",
+    "    test.test_reversed(reverse_string)\n",
+    "    test.test_reversed(reverse_string_alt)\n",
+    "    test.test_reversed(reverse_string_alt2)"
    ]
   },
   {