Added bug description to new test case

Jon M. Mease · Jon M. Mease · commit 5cfa7c6dc9e1 · 2016-10-19T19:55:56.000-04:00
diff --git a/pandas/tests/test_groupby.py b/pandas/tests/test_groupby.py
@@ -443,6 +443,7 @@ def test_grouper_creation_bug(self):
         assert_frame_equal(result, expected)
 
         # GH14334
+        # pd.Grouper(key=...) may be passed in a list
         g = df.groupby([pd.Grouper(key='A')])
         result = g.sum()
         assert_frame_equal(result, expected)
