changed according to comments

doc/source/whatsnew/v0.24.0.txt

@@ -185,7 +185,7 @@ Numeric
 ^^^^^^^
 
 - Bug in :class:`Series` ``__rmatmul__`` doesn't support matrix vector multiplication (:issue:`21530`)
--
+- :meth:`~DataFrame.agg` now handles built-in methods like ``sum`` with axis=1 (:issue:`21224`)
 -
 
 Strings

pandas/conftest.py

@@ -54,6 +54,21 @@ def spmatrix(request):
     return getattr(sparse, request.param + '_matrix')
 
 
+@pytest.fixture(params=[0, 1],
+                ids=lambda x: "axis {}".format(x))
+def axis(request):
+    """
+     Fixture for returning the axis numbers of a dataframe.
+     """
+    return request.param
+
+@pytest.fixture(params=[0], ids=lambda x: "axis {}".format(x))
+def axis_series(request):
+    """
+     Fixture for returning the axis numbers of a series.
+     """
+    return request.param
+
 @pytest.fixture
 def ip():
     """

pandas/core/indexing.py

@@ -1829,7 +1829,7 @@ def error():
                     error()
                 raise
             except:
-                raise
+                raise error()
 
             if not ax.contains(key):
                 error()

pandas/tests/frame/test_analytics.py

@@ -2094,7 +2094,6 @@ def test_clip_against_list_like(self, inplace, lower, axis, res):
     @pytest.mark.xfail(
         not _np_version_under1p15,
         reason="failing under numpy-dev gh-19976")
-    @pytest.mark.parametrize("axis", [0, 1, None])
     def test_clip_against_frame(self, axis):
         df = DataFrame(np.random.randn(1000, 2))
         lb = DataFrame(np.random.randn(1000, 2))

pandas/tests/generic/test_label_or_level_utils.py

@@ -76,7 +76,6 @@ def assert_level_reference(frame, levels, axis):
 
 # DataFrame
 # ---------
-@pytest.mark.parametrize('axis', [0, 1])
 def test_is_level_or_label_reference_df_simple(df_levels, axis):
 
     # Compute expected labels and levels
@@ -91,7 +90,6 @@ def test_is_level_or_label_reference_df_simple(df_levels, axis):
     assert_label_reference(df_levels, expected_labels, axis=axis)
 
 
-@pytest.mark.parametrize('axis', [0, 1])
 def test_is_level_reference_df_ambig(df_ambig, axis):
 
     # Transpose frame if axis == 1
@@ -165,7 +163,6 @@ def test_is_label_or_level_reference_panel_error(panel):
 
 # DataFrame
 # ---------
-@pytest.mark.parametrize('axis', [0, 1])
 def test_check_label_or_level_ambiguity_df(df_ambig, axis):
 
     # Transpose frame if axis == 1
@@ -264,7 +261,6 @@ def assert_level_values(frame, levels, axis):
 
 # DataFrame
 # ---------
-@pytest.mark.parametrize('axis', [0, 1])
 def test_get_label_or_level_values_df_simple(df_levels, axis):
 
     # Compute expected labels and levels
@@ -279,7 +275,6 @@ def test_get_label_or_level_values_df_simple(df_levels, axis):
     assert_level_values(df_levels, expected_levels, axis=axis)
 
 
-@pytest.mark.parametrize('axis', [0, 1])
 def test_get_label_or_level_values_df_ambig(df_ambig, axis):
 
     # Transpose frame if axis == 1
@@ -300,7 +295,6 @@ def test_get_label_or_level_values_df_ambig(df_ambig, axis):
         assert_label_values(df_ambig, ['L3'], axis=axis)
 
 
-@pytest.mark.parametrize('axis', [0, 1])
 def test_get_label_or_level_values_df_duplabels(df_duplabels, axis):
 
     # Transpose frame if axis == 1
@@ -383,7 +377,6 @@ def assert_levels_dropped(frame, levels, axis):
 
 # DataFrame
 # ---------
-@pytest.mark.parametrize('axis', [0, 1])
 def test_drop_labels_or_levels_df(df_levels, axis):
 
     # Compute expected labels and levels