ensure consistency between columns aggregates with missing values present (pandas-dev#29345)

Author: mjarosie

pandas/tests/frame/test_apply.py

@@ -1359,3 +1359,14 @@ def test_apply_datetime_tz_issue(self):
         expected = pd.Series(index=timestamps, data=timestamps)
 
         tm.assert_series_equal(result, expected)
+
+    @pytest.mark.parametrize("df", [pd.DataFrame({"A": ["a", None], "B": ["c", "d"]})])
+    @pytest.mark.parametrize("method", ["min", "max", "sum"])
+    def test_consistency_of_aggregates_of_columns_with_missing_values(self, df, method):
+        # GH 16832
+        none_in_first_column_result = getattr(df[["A", "B"]], method)()
+        none_in_second_column_result = getattr(df[["B", "A"]], method)()
+
+        tm.assert_series_equal(
+            none_in_first_column_result, none_in_second_column_result
+        )