TST: period-like test for GH9012

Author: jreback

doc/source/whatsnew/v0.15.2.txt

@@ -271,3 +271,4 @@ Bug Fixes
 - Bug in plotting if sharex was enabled and index was a timeseries, would show labels on multiple axes (:issue:`3964`).
 
 - Bug where passing a unit to the TimedeltaIndex constructor applied the to nano-second conversion twice. (:issue:`9011`).
+- Bug in plotting of a period-like array (:issue:`9012`)

pandas/tests/test_graphics.py

@@ -9,7 +9,8 @@
 
 from datetime import datetime, date
 
-from pandas import Series, DataFrame, MultiIndex, PeriodIndex, date_range
+from pandas import (Series, DataFrame, MultiIndex, PeriodIndex, date_range,
+                    bdate_range)
 from pandas.compat import (range, lrange, StringIO, lmap, lzip, u, zip,
                            iteritems, OrderedDict, PY3)
 from pandas.util.decorators import cache_readonly
@@ -1152,6 +1153,18 @@ def test_xcompat(self):
         self.assertNotIsInstance(lines[0].get_xdata(), PeriodIndex)
         self.assertIsInstance(PeriodIndex(lines[0].get_xdata()), PeriodIndex)
 
+    def test_period_compat(self):
+        # GH 9012
+        # period-array conversions
+        df = DataFrame(
+            np.random.rand(21, 2),
+            index=bdate_range(datetime(2000, 1, 1), datetime(2000, 1, 31)),
+            columns=['a', 'b'])
+
+        df.plot()
+        self.plt.axhline(y=0)
+        tm.close()
+
     def test_unsorted_index(self):
         df = DataFrame({'y': np.arange(100)},
                        index=np.arange(99, -1, -1), dtype=np.int64)