Add test for dates in mpl.

Author: theengineear

plotly/tests/test_optional/test_matplotlylib/test_date_times.py

@@ -0,0 +1,40 @@
+from __future__ import absolute_import
+import matplotlib
+# Force matplotlib to not use any Xwindows backend.
+matplotlib.use('Agg')
+import matplotlib.pyplot as plt
+import datetime
+from matplotlib.dates import date2num
+import plotly.tools as tls
+from unittest import TestCase
+
+from plotly.tests.test_optional.optional_utils import compare_dict, run_fig
+
+
+class TestDateTimes(TestCase):
+    def test_normal_mpl_dates(self):
+        datetime_format = '%Y-%m-%d %H:%M:%S'
+        y = [1, 2, 3, 4]
+        date_strings = ['2010-01-04 00:00:00',
+                        '2010-01-04 10:00:00',
+                        '2010-01-04 23:00:59',
+                        '2010-01-05 00:00:00']
+
+        # 1. create datetimes from the strings
+        dates = [datetime.datetime.strptime(date_string, datetime_format)
+                 for date_string in date_strings]
+
+        # 2. create the mpl_dates from these datetimes
+        mpl_dates = date2num(dates)
+
+        # make a figure in mpl
+        fig, ax = plt.subplots()
+        ax.plot_date(mpl_dates, y)
+
+        # convert this figure to plotly's graph_objs
+        pfig = tls.mpl_to_plotly(fig)
+
+        print date_strings
+        print pfig['data'][0]['x']
+        # we use the same format here, so we expect equality here
+        self.assertEqual(pfig['data'][0]['x'], date_strings)