Finish up the section on TDD

diff --git a/python/sw_engineering/SoftwareEngineering.ipynb b/python/sw_engineering/SoftwareEngineering.ipynb
index 6c714f1224a3c2d8390fe3bf07ecc23a7132d4bd..bdfd76321e981cbfa5e70d9e0b68f85e04d950ff 100644 (file)
--- a/python/sw_engineering/SoftwareEngineering.ipynb
+++ b/python/sw_engineering/SoftwareEngineering.ipynb
@@ -1890,31 +1890,139 @@
       "* A list of all zeros\n",
       "* Integers with an integral mean\n",
       "* Integers with a non-integral mean\n",
-      "* Floating point numbers\n",
+      "* Floating point numbers"
+     ]
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "## Results\n",
       "\n",
-      "TBD: empty list? exception?"
+      "You probably wound up with something like this."
      ]
     },
     {
      "cell_type": "code",
      "collapsed": false,
      "input": [
-      "def calc_mean(ilist):\n",
-      "    '''\n",
-      "    returns the mean of input list\n",
-      "    '''\n",
-      "    if len(ilist) == 0:\n",
-      "        raise ValueError('Input is empty.')\n",
-      "        \n",
+      "def mean(numbers):\n",
+      "    '''Returns the mean of the provided list of numbers.'''\n",
       "    total = 0.0\n",
-      "    for num in ilist:\n",
-      "        total = total + num\n",
-      "    return total/float(len(ilist))"
+      "    for number in numbers:\n",
+      "        total = total + number\n",
+      "    return total/float(len(numbers))"
      ],
      "language": "python",
      "metadata": {},
      "outputs": [],
-     "prompt_number": 27
+     "prompt_number": 1
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "How good was your testing?"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "mean([0])"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "pyout",
+       "prompt_number": 2,
+       "text": [
+        "0.0"
+       ]
+      }
+     ],
+     "prompt_number": 2
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "mean([1])"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "pyout",
+       "prompt_number": 5,
+       "text": [
+        "1.0"
+       ]
+      }
+     ],
+     "prompt_number": 5
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "mean([1, 2, 3, 4, 5])"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "pyout",
+       "prompt_number": 3,
+       "text": [
+        "3.0"
+       ]
+      }
+     ],
+     "prompt_number": 3
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "mean([2.7, 3.8, 7.2])"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "pyout",
+       "prompt_number": 4,
+       "text": [
+        "4.566666666666666"
+       ]
+      }
+     ],
+     "prompt_number": 4
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "mean([])"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "ename": "ZeroDivisionError",
+       "evalue": "float division by zero",
+       "output_type": "pyerr",
+       "traceback": [
+        "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m\n\u001b[0;31mZeroDivisionError\u001b[0m                         Traceback (most recent call last)",
+        "\u001b[0;32m<ipython-input-6-e9e2222d800d>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m()\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0mmean\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0;34m]\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
+        "\u001b[0;32m<ipython-input-1-16ccb79ef6d8>\u001b[0m in \u001b[0;36mmean\u001b[0;34m(numbers)\u001b[0m\n\u001b[1;32m      4\u001b[0m     \u001b[0;32mfor\u001b[0m \u001b[0mnumber\u001b[0m \u001b[0;32min\u001b[0m \u001b[0mnumbers\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m      5\u001b[0m         \u001b[0mtotal\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mtotal\u001b[0m \u001b[0;34m+\u001b[0m \u001b[0mnumber\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 6\u001b[0;31m     \u001b[0;32mreturn\u001b[0m \u001b[0mtotal\u001b[0m\u001b[0;34m/\u001b[0m\u001b[0mfloat\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mlen\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mnumbers\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
+        "\u001b[0;31mZeroDivisionError\u001b[0m: float division by zero"
+       ]
+      }
+     ],
+     "prompt_number": 6
     },
     {
      "cell_type": "code",