fixup! Add test for DataFrame.agg with *args, **kwargs

Author: pganssle

pandas/tests/frame/apply/test_frame_apply.py

@@ -1483,13 +1483,13 @@ def f(x, a, b, c=3):
         df = pd.DataFrame([[1, 2], [3, 4]])
 
         if axis == 0:
-            expected = pd.DataFrame([5.0, 7.0])
+            expected = pd.Series([5.0, 7.0])
         else:
-            expected = pd.DataFrame([4.0, 8.0])
+            expected = pd.Series([4.0, 8.0])
 
         result = df.agg(f, axis, *args, **kwargs)
 
-        tm.assert_frame_equal(result, expected)
+        tm.assert_series_equal(result, expected)
 
     @pytest.mark.parametrize("num_cols", [2, 3, 5])
     def test_frequency_is_original(self, num_cols):