From 4e18c8276ff3a8e517c98a5989840ac7e2feba1e Mon Sep 17 00:00:00 2001
From: peadarcoyle <peadarcoyle@googlemail.com>
Date: Mon, 27 Oct 2014 23:33:26 +0100
Subject: [PATCH] Updating tests file Cleaning up

---
 pandas/core/generic.py       |  6 ++++--
 pandas/tests/test_groupby.py | 18 ++++++++++++++++--
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 52f37ee24f69a..059cdff8996f7 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -2875,10 +2875,12 @@ def groupby(self, by=None, axis=0, level=None, as_index=True, sort=True,
         GroupBy object
 
         """
-
         from pandas.core.groupby import groupby
+
+        if level is None and by is None:
+            raise TypeError("You have to supply one of 'by' and 'level'")
         axis = self._get_axis_number(axis)
-        return groupby(self, by, axis=axis, level=level, as_index=as_index,
+        return groupby(self, by=by, axis=axis, level=level, as_index=as_index,
                        sort=sort, group_keys=group_keys, squeeze=squeeze)
 
     def asfreq(self, freq, method=None, how=None, normalize=False):
diff --git a/pandas/tests/test_groupby.py b/pandas/tests/test_groupby.py
index ef3fc03fc8d22..bf24eda60b986 100644
--- a/pandas/tests/test_groupby.py
+++ b/pandas/tests/test_groupby.py
@@ -1961,6 +1961,9 @@ def test_groupby_level(self):
         # raise exception for non-MultiIndex
         self.assertRaises(ValueError, self.df.groupby, level=1)
 
+
+
+
     def test_groupby_level_index_names(self):
         ## GH4014 this used to raise ValueError since 'exp'>1 (in py2)
         df = DataFrame({'exp' : ['A']*3 + ['B']*3, 'var1' : lrange(6),}).set_index('exp')
@@ -1999,6 +2002,17 @@ def test_groupby_level_apply(self):
         result = frame['A'].groupby(level=0).count()
         self.assertEqual(result.index.name, 'first')
 
+    def test_groupby_args(self):
+        #PR8618 and issue 8015
+        frame = self.mframe
+        def j():
+             frame.groupby()
+        self.assertRaisesRegexp(TypeError, "You have to supply one of 'by' and 'level'", j)
+
+        def k():
+            frame.groupby(by=None, level=None)
+        self.assertRaisesRegexp(TypeError,  "You have to supply one of 'by' and 'level'", k)
+
     def test_groupby_level_mapper(self):
         frame = self.mframe
         deleveled = frame.reset_index()
@@ -3689,8 +3703,8 @@ def test_cumcount(self):
         assert_series_equal(expected, sg.cumcount())
 
     def test_cumcount_empty(self):
-        ge = DataFrame().groupby()
-        se = Series().groupby()
+        ge = DataFrame().groupby(level=0)
+        se = Series().groupby(level=0)
 
         e = Series(dtype='int64')  # edge case, as this is usually considered float