TST: Fix tests which used tuples to pass multiple keys

Author: toobaz

pandas/tests/groupby/test_groupby.py

@@ -264,7 +264,7 @@ def test_len(self):
         df = pd.DataFrame(dict(a=[np.nan] * 3, b=[1, 2, 3]))
         assert len(df.groupby(('a'))) == 0
         assert len(df.groupby(('b'))) == 3
-        assert len(df.groupby(('a', 'b'))) == 3
+        assert len(df.groupby(['a', 'b'])) == 3
 
     def test_basic_regression(self):
         # regression

pandas/tests/groupby/test_nth.py

@@ -202,7 +202,7 @@ def test_nth(self):
                                        freq='B')
         df = DataFrame(1, index=business_dates, columns=['a', 'b'])
         # get the first, fourth and last two business days for each month
-        key = (df.index.year, df.index.month)
+        key = [df.index.year, df.index.month]
         result = df.groupby(key, as_index=False).nth([0, 3, -2, -1])
         expected_dates = pd.to_datetime(
             ['2014/4/1', '2014/4/4', '2014/4/29', '2014/4/30', '2014/5/1',

pandas/tests/groupby/test_value_counts.py

@@ -43,7 +43,7 @@ def seed_df(seed_nans, n, m):
 
         df = seed_df(seed_nans, n, m)
         bins = None, np.arange(0, max(5, df['3rd'].max()) + 1, 2)
-        keys = '1st', '2nd', ('1st', '2nd')
+        keys = '1st', '2nd', ['1st', '2nd']
         for k, b in product(keys, bins):
             binned.append((df, k, b, n, m))
             ids.append("{}-{}-{}".format(k, n, m))