Add more on nbval

Author: trallard

03_ProcessData.ipynb

@@ -919,7 +919,7 @@
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 3",
+   "display_name": "Python [default]",
    "language": "python",
    "name": "python3"
   },

04_Testing.ipynb

@@ -347,7 +347,7 @@
     }
    },
    "source": [
-    "# nbval\n",
+    "## Testing Jupyter notebooks with nbval\n",
     "\n",
     "We first need to understand how a Jupyter notebook works. \n",
     "All the data is stored in a .json like format (organised key, data values)... this includes the results, code, and markdown.\n",
@@ -378,6 +378,35 @@
     "```"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Since we have a timestamp in the notebook (`time.strftime('%H:%M:%S'))`) and the test is performed at a different time, the tests will fail. \n",
+    "\n",
+    "We can avoid this by providing a sanitizing file `sanitize.cfg`:\n",
+    "<pre><code>\n",
+    "[regex1]\n",
+    "regex: \\d{1,2}/\\d{1,2}/\\d{2,4}\n",
+    "replace: DATE-STAMP\n",
+    "[regex2]\n",
+    "regex: \\d{2}:\\d{2}:\\d{2}\n",
+    "replace: TIME-STAMP\n",
+    "</pre></code>\n",
+    "\n",
+    "This will identify time and data stamp like data in your notebooks. Then you can re run the test using:\n",
+    "<pre><code>\n",
+    "py.test --nbval demo.ipynb --sanitize-with sanitize_nb.cfg\n",
+    "</pre></code>\n",
+    "\n",
+    "If you are only interested in verifying if your notebooks <strong>are broken or not</strong> (check for exceptions)\n",
+    "you can use `--nbval-lax` which runs notebooks and checks for errors, but only compares the outputs of cells with a `#NBVAL_CHECK_OUTPUT` marker comment.\n",
+    "<pre><code>\n",
+    "$ py.test --nbval-lax classify-demo.ipynb\n",
+    "</pre></code>\n",
+    "\n"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -567,7 +596,7 @@
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 3",
+   "display_name": "Python [default]",
    "language": "python",
    "name": "python3"
   },