WIP

Author: rhshadrach

pandas/core/groupby/generic.py

@@ -1714,7 +1714,7 @@ def _python_agg_general(self, func, *args, **kwargs):
 
         obj = self._obj_with_exclusions
 
-        if not len(obj.columns):
+        if self._grouper._is_resample and not len(obj.columns):
             # e.g. test_margins_no_values_no_cols
             return self._python_apply_general(f, self._selected_obj)
 

pandas/tests/reshape/test_pivot.py

@@ -1198,8 +1198,15 @@ def test_margins_no_values_no_cols(self, data):
         result = data[["A", "B"]].pivot_table(
             index=["A", "B"], aggfunc=len, margins=True
         )
-        result_list = result.tolist()
-        assert sum(result_list[:-1]) == result_list[-1]
+        expected = DataFrame(
+            index=MultiIndex(
+                levels=[["bar", "foo", "All"], ["one", "two", ""]],
+                codes=[[0, 0, 1, 1, 2], [0, 1, 0, 1, 2]],
+                names=["A", "B"],
+            ),
+            columns=Index([]),
+        )
+        tm.assert_frame_equal(result, expected)
 
     def test_margins_no_values_two_rows(self, data):
         # Regression test on pivot table: no values passed but rows are a