From 373cc20a147c57dc671a441d7e57e25f91503613 Mon Sep 17 00:00:00 2001
From: Nathan Goldbaum <nathan.goldbaum@gmail.com>
Date: Fri, 25 Jul 2025 09:36:54 -0600
Subject: [PATCH 01/12] TST: run python-dev CI on 3.14-dev

---
 .github/workflows/unit-tests.yml | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/.github/workflows/unit-tests.yml b/.github/workflows/unit-tests.yml
index 7bee8474d4db5..beedcd92c467d 100644
--- a/.github/workflows/unit-tests.yml
+++ b/.github/workflows/unit-tests.yml
@@ -313,7 +313,6 @@ jobs:
     #    To freeze this file, uncomment out the ``if: false`` condition, and migrate the jobs
     #    to the corresponding posix/windows-macos/sdist etc. workflows.
     # Feel free to modify this comment as necessary.
-    if: false
     defaults:
       run:
         shell: bash -eou pipefail {0}
@@ -345,7 +344,7 @@ jobs:
       - name: Set up Python Dev Version
         uses: actions/setup-python@v5
         with:
-          python-version: '3.13-dev'
+          python-version: '3.14-dev'
 
       - name: Build Environment
         run: |

From 05bb5eccba526be169c989ff240edc69264fa8dc Mon Sep 17 00:00:00 2001
From: Nathan Goldbaum <nathan.goldbaum@gmail.com>
Date: Fri, 25 Jul 2025 13:16:40 -0600
Subject: [PATCH 02/12] MAINT: disable the warning on 3.14 and newer

---
 pandas/core/frame.py    |  4 ++--
 pandas/core/generic.py  | 16 ++++++++--------
 pandas/core/indexing.py |  2 +-
 pandas/core/series.py   |  4 ++--
 4 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/pandas/core/frame.py b/pandas/core/frame.py
index e48620a854edb..0459c655dd393 100644
--- a/pandas/core/frame.py
+++ b/pandas/core/frame.py
@@ -4296,7 +4296,7 @@ def __setitem__(self, key, value) -> None:
         z  3  50
         # Values for 'a' and 'b' are completely ignored!
         """
-        if not PYPY:
+        if not PYPY and sys.version_info < (3, 14):
             if sys.getrefcount(self) <= 3:
                 warnings.warn(
                     _chained_assignment_msg, ChainedAssignmentError, stacklevel=2
@@ -9204,7 +9204,7 @@ def update(
         1  2  500.0
         2  3    6.0
         """
-        if not PYPY:
+        if not PYPY and sys.version_info < (3, 14):
             if sys.getrefcount(self) <= REF_COUNT:
                 warnings.warn(
                     _chained_assignment_method_msg,
diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 2ae28266266f6..3b8dab6f0068b 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -7069,7 +7069,7 @@ def fillna(
         """
         inplace = validate_bool_kwarg(inplace, "inplace")
         if inplace:
-            if not PYPY:
+            if not PYPY and sys.version_info < (3, 14):
                 if sys.getrefcount(self) <= REF_COUNT:
                     warnings.warn(
                         _chained_assignment_method_msg,
@@ -7300,7 +7300,7 @@ def ffill(
         """
         inplace = validate_bool_kwarg(inplace, "inplace")
         if inplace:
-            if not PYPY:
+            if not PYPY and sys.version_info < (3, 14):
                 if sys.getrefcount(self) <= REF_COUNT:
                     warnings.warn(
                         _chained_assignment_method_msg,
@@ -7440,7 +7440,7 @@ def bfill(
         """
         inplace = validate_bool_kwarg(inplace, "inplace")
         if inplace:
-            if not PYPY:
+            if not PYPY and sys.version_info < (3, 14):
                 if sys.getrefcount(self) <= REF_COUNT:
                     warnings.warn(
                         _chained_assignment_method_msg,
@@ -7525,7 +7525,7 @@ def replace(
 
         inplace = validate_bool_kwarg(inplace, "inplace")
         if inplace:
-            if not PYPY:
+            if not PYPY and sys.version_info < (3, 14):
                 if sys.getrefcount(self) <= REF_COUNT:
                     warnings.warn(
                         _chained_assignment_method_msg,
@@ -7888,7 +7888,7 @@ def interpolate(
         inplace = validate_bool_kwarg(inplace, "inplace")
 
         if inplace:
-            if not PYPY:
+            if not PYPY and sys.version_info < (3, 14):
                 if sys.getrefcount(self) <= REF_COUNT:
                     warnings.warn(
                         _chained_assignment_method_msg,
@@ -8472,7 +8472,7 @@ def clip(
         inplace = validate_bool_kwarg(inplace, "inplace")
 
         if inplace:
-            if not PYPY:
+            if not PYPY and sys.version_info < (3, 14):
                 if sys.getrefcount(self) <= REF_COUNT:
                     warnings.warn(
                         _chained_assignment_method_msg,
@@ -10081,7 +10081,7 @@ def where(
         """
         inplace = validate_bool_kwarg(inplace, "inplace")
         if inplace:
-            if not PYPY:
+            if not PYPY and sys.version_info < (3, 14):
                 if sys.getrefcount(self) <= REF_COUNT:
                     warnings.warn(
                         _chained_assignment_method_msg,
@@ -10145,7 +10145,7 @@ def mask(
     ) -> Self | None:
         inplace = validate_bool_kwarg(inplace, "inplace")
         if inplace:
-            if not PYPY:
+            if not PYPY and sys.version_info < (3, 14):
                 if sys.getrefcount(self) <= REF_COUNT:
                     warnings.warn(
                         _chained_assignment_method_msg,
diff --git a/pandas/core/indexing.py b/pandas/core/indexing.py
index 42dd8adbead09..6c3e5971a4ded 100644
--- a/pandas/core/indexing.py
+++ b/pandas/core/indexing.py
@@ -913,7 +913,7 @@ def _ensure_listlike_indexer(self, key, axis=None, value=None) -> None:
 
     @final
     def __setitem__(self, key, value) -> None:
-        if not PYPY:
+        if not PYPY and sys.version_info < (3, 14):
             if sys.getrefcount(self.obj) <= 2:
                 warnings.warn(
                     _chained_assignment_msg, ChainedAssignmentError, stacklevel=2
diff --git a/pandas/core/series.py b/pandas/core/series.py
index 6ae03f2464f76..abf900a094d2d 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -1059,7 +1059,7 @@ def _get_value(self, label, takeable: bool = False):
             return self.iloc[loc]
 
     def __setitem__(self, key, value) -> None:
-        if not PYPY:
+        if not PYPY and sys.version_info < (3, 14):
             if sys.getrefcount(self) <= 3:
                 warnings.warn(
                     _chained_assignment_msg, ChainedAssignmentError, stacklevel=2
@@ -3338,7 +3338,7 @@ def update(self, other: Series | Sequence | Mapping) -> None:
         2    3
         dtype: int64
         """
-        if not PYPY:
+        if not PYPY and sys.version_info < (3, 14):
             if sys.getrefcount(self) <= REF_COUNT:
                 warnings.warn(
                     _chained_assignment_method_msg,

From d7a139b5fe75da85c60dc93fc9bff76c30b78d80 Mon Sep 17 00:00:00 2001
From: Nathan Goldbaum <nathan.goldbaum@gmail.com>
Date: Thu, 7 Aug 2025 14:32:12 -0600
Subject: [PATCH 03/12] MNT: use REF_COUNT instead of magic constants

---
 pandas/compat/_constants.py | 9 ++++++++-
 pandas/core/frame.py        | 2 +-
 pandas/core/indexing.py     | 3 ++-
 pandas/core/series.py       | 2 +-
 4 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/pandas/compat/_constants.py b/pandas/compat/_constants.py
index c7b7341013251..616934f66a3d3 100644
--- a/pandas/compat/_constants.py
+++ b/pandas/compat/_constants.py
@@ -15,10 +15,17 @@
 
 PY311 = sys.version_info >= (3, 11)
 PY312 = sys.version_info >= (3, 12)
+PY314 = sys.version_info >= (3, 14)
 PYPY = platform.python_implementation() == "PyPy"
 WASM = (sys.platform == "emscripten") or (platform.machine() in ["wasm32", "wasm64"])
 ISMUSL = "musl" in (sysconfig.get_config_var("HOST_GNU_TYPE") or "")
-REF_COUNT = 2 if PY311 else 3
+if PY311:
+    REF_COUNT = 2
+elif PY314:
+    REF_COUNT = 1
+else:
+    # Python 3.10 and older
+    REF_COUNT = 3
 
 __all__ = [
     "IS64",
diff --git a/pandas/core/frame.py b/pandas/core/frame.py
index 0459c655dd393..393e934adf498 100644
--- a/pandas/core/frame.py
+++ b/pandas/core/frame.py
@@ -4297,7 +4297,7 @@ def __setitem__(self, key, value) -> None:
         # Values for 'a' and 'b' are completely ignored!
         """
         if not PYPY and sys.version_info < (3, 14):
-            if sys.getrefcount(self) <= 3:
+            if sys.getrefcount(self) <= REF_COUNT + 1:
                 warnings.warn(
                     _chained_assignment_msg, ChainedAssignmentError, stacklevel=2
                 )
diff --git a/pandas/core/indexing.py b/pandas/core/indexing.py
index 6c3e5971a4ded..24716dd875c37 100644
--- a/pandas/core/indexing.py
+++ b/pandas/core/indexing.py
@@ -15,6 +15,7 @@
 from pandas._libs.indexing import NDFrameIndexerBase
 from pandas._libs.lib import item_from_zerodim
 from pandas.compat import PYPY
+from pandas.compat._constants import REF_COUNT
 from pandas.errors import (
     AbstractMethodError,
     ChainedAssignmentError,
@@ -914,7 +915,7 @@ def _ensure_listlike_indexer(self, key, axis=None, value=None) -> None:
     @final
     def __setitem__(self, key, value) -> None:
         if not PYPY and sys.version_info < (3, 14):
-            if sys.getrefcount(self.obj) <= 2:
+            if sys.getrefcount(self.obj) <= REF_COUNT:
                 warnings.warn(
                     _chained_assignment_msg, ChainedAssignmentError, stacklevel=2
                 )
diff --git a/pandas/core/series.py b/pandas/core/series.py
index abf900a094d2d..c6284bcfbc374 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -1060,7 +1060,7 @@ def _get_value(self, label, takeable: bool = False):
 
     def __setitem__(self, key, value) -> None:
         if not PYPY and sys.version_info < (3, 14):
-            if sys.getrefcount(self) <= 3:
+            if sys.getrefcount(self) <= REF_COUNT + 1:
                 warnings.warn(
                     _chained_assignment_msg, ChainedAssignmentError, stacklevel=2
                 )

From b5b3d2e5b5938a673559cdb3ff4e1b43ecc965e4 Mon Sep 17 00:00:00 2001
From: Nathan Goldbaum <nathan.goldbaum@gmail.com>
Date: Thu, 7 Aug 2025 14:39:52 -0600
Subject: [PATCH 04/12] MNT: use a global constant for disabling the warning

---
 pandas/compat/_constants.py | 10 +++-------
 pandas/core/frame.py        |  6 +++---
 pandas/core/generic.py      | 18 +++++++++---------
 pandas/core/indexing.py     |  4 ++--
 pandas/core/series.py       |  6 +++---
 5 files changed, 20 insertions(+), 24 deletions(-)

diff --git a/pandas/compat/_constants.py b/pandas/compat/_constants.py
index 616934f66a3d3..9f230dbeec97c 100644
--- a/pandas/compat/_constants.py
+++ b/pandas/compat/_constants.py
@@ -19,13 +19,9 @@
 PYPY = platform.python_implementation() == "PyPy"
 WASM = (sys.platform == "emscripten") or (platform.machine() in ["wasm32", "wasm64"])
 ISMUSL = "musl" in (sysconfig.get_config_var("HOST_GNU_TYPE") or "")
-if PY311:
-    REF_COUNT = 2
-elif PY314:
-    REF_COUNT = 1
-else:
-    # Python 3.10 and older
-    REF_COUNT = 3
+REF_COUNT = 2 if PY311 else 3
+# hopefully there is a workaround in Python 3.14.1
+WARNING_CHECK_BROKEN = PY314
 
 __all__ = [
     "IS64",
diff --git a/pandas/core/frame.py b/pandas/core/frame.py
index 393e934adf498..6cf99e9f6279a 100644
--- a/pandas/core/frame.py
+++ b/pandas/core/frame.py
@@ -49,7 +49,7 @@
 from pandas._libs.hashtable import duplicated
 from pandas._libs.lib import is_range_indexer
 from pandas.compat import PYPY
-from pandas.compat._constants import REF_COUNT
+from pandas.compat._constants import REF_COUNT, WARNING_CHECK_BROKEN
 from pandas.compat._optional import import_optional_dependency
 from pandas.compat.numpy import function as nv
 from pandas.errors import (
@@ -4296,7 +4296,7 @@ def __setitem__(self, key, value) -> None:
         z  3  50
         # Values for 'a' and 'b' are completely ignored!
         """
-        if not PYPY and sys.version_info < (3, 14):
+        if not PYPY and not WARNING_CHECK_BROKEN:
             if sys.getrefcount(self) <= REF_COUNT + 1:
                 warnings.warn(
                     _chained_assignment_msg, ChainedAssignmentError, stacklevel=2
@@ -9204,7 +9204,7 @@ def update(
         1  2  500.0
         2  3    6.0
         """
-        if not PYPY and sys.version_info < (3, 14):
+        if not PYPY and not WARNING_CHECK_BROKEN:
             if sys.getrefcount(self) <= REF_COUNT:
                 warnings.warn(
                     _chained_assignment_method_msg,
diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 3b8dab6f0068b..0768e3048238d 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -83,7 +83,7 @@
     npt,
 )
 from pandas.compat import PYPY
-from pandas.compat._constants import REF_COUNT
+from pandas.compat._constants import REF_COUNT, WARNING_CHECK_BROKEN
 from pandas.compat._optional import import_optional_dependency
 from pandas.compat.numpy import function as nv
 from pandas.errors import (
@@ -7069,7 +7069,7 @@ def fillna(
         """
         inplace = validate_bool_kwarg(inplace, "inplace")
         if inplace:
-            if not PYPY and sys.version_info < (3, 14):
+            if not PYPY and WARNING_CHECK_BROKEN:
                 if sys.getrefcount(self) <= REF_COUNT:
                     warnings.warn(
                         _chained_assignment_method_msg,
@@ -7300,7 +7300,7 @@ def ffill(
         """
         inplace = validate_bool_kwarg(inplace, "inplace")
         if inplace:
-            if not PYPY and sys.version_info < (3, 14):
+            if not PYPY and WARNING_CHECK_BROKEN:
                 if sys.getrefcount(self) <= REF_COUNT:
                     warnings.warn(
                         _chained_assignment_method_msg,
@@ -7440,7 +7440,7 @@ def bfill(
         """
         inplace = validate_bool_kwarg(inplace, "inplace")
         if inplace:
-            if not PYPY and sys.version_info < (3, 14):
+            if not PYPY and WARNING_CHECK_BROKEN:
                 if sys.getrefcount(self) <= REF_COUNT:
                     warnings.warn(
                         _chained_assignment_method_msg,
@@ -7525,7 +7525,7 @@ def replace(
 
         inplace = validate_bool_kwarg(inplace, "inplace")
         if inplace:
-            if not PYPY and sys.version_info < (3, 14):
+            if not PYPY and WARNING_CHECK_BROKEN:
                 if sys.getrefcount(self) <= REF_COUNT:
                     warnings.warn(
                         _chained_assignment_method_msg,
@@ -7888,7 +7888,7 @@ def interpolate(
         inplace = validate_bool_kwarg(inplace, "inplace")
 
         if inplace:
-            if not PYPY and sys.version_info < (3, 14):
+            if not PYPY and WARNING_CHECK_BROKEN:
                 if sys.getrefcount(self) <= REF_COUNT:
                     warnings.warn(
                         _chained_assignment_method_msg,
@@ -8472,7 +8472,7 @@ def clip(
         inplace = validate_bool_kwarg(inplace, "inplace")
 
         if inplace:
-            if not PYPY and sys.version_info < (3, 14):
+            if not PYPY and WARNING_CHECK_BROKEN:
                 if sys.getrefcount(self) <= REF_COUNT:
                     warnings.warn(
                         _chained_assignment_method_msg,
@@ -10081,7 +10081,7 @@ def where(
         """
         inplace = validate_bool_kwarg(inplace, "inplace")
         if inplace:
-            if not PYPY and sys.version_info < (3, 14):
+            if not PYPY and WARNING_CHECK_BROKEN:
                 if sys.getrefcount(self) <= REF_COUNT:
                     warnings.warn(
                         _chained_assignment_method_msg,
@@ -10145,7 +10145,7 @@ def mask(
     ) -> Self | None:
         inplace = validate_bool_kwarg(inplace, "inplace")
         if inplace:
-            if not PYPY and sys.version_info < (3, 14):
+            if not PYPY and WARNING_CHECK_BROKEN:
                 if sys.getrefcount(self) <= REF_COUNT:
                     warnings.warn(
                         _chained_assignment_method_msg,
diff --git a/pandas/core/indexing.py b/pandas/core/indexing.py
index 24716dd875c37..f6cb82c239edc 100644
--- a/pandas/core/indexing.py
+++ b/pandas/core/indexing.py
@@ -15,7 +15,7 @@
 from pandas._libs.indexing import NDFrameIndexerBase
 from pandas._libs.lib import item_from_zerodim
 from pandas.compat import PYPY
-from pandas.compat._constants import REF_COUNT
+from pandas.compat._constants import REF_COUNT, WARNING_CHECK_BROKEN
 from pandas.errors import (
     AbstractMethodError,
     ChainedAssignmentError,
@@ -914,7 +914,7 @@ def _ensure_listlike_indexer(self, key, axis=None, value=None) -> None:
 
     @final
     def __setitem__(self, key, value) -> None:
-        if not PYPY and sys.version_info < (3, 14):
+        if not PYPY and not WARNING_CHECK_BROKEN:
             if sys.getrefcount(self.obj) <= REF_COUNT:
                 warnings.warn(
                     _chained_assignment_msg, ChainedAssignmentError, stacklevel=2
diff --git a/pandas/core/series.py b/pandas/core/series.py
index c6284bcfbc374..2c7c7ca8ee11e 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -34,7 +34,7 @@
 )
 from pandas._libs.lib import is_range_indexer
 from pandas.compat import PYPY
-from pandas.compat._constants import REF_COUNT
+from pandas.compat._constants import REF_COUNT, WARNING_CHECK_BROKEN
 from pandas.compat._optional import import_optional_dependency
 from pandas.compat.numpy import function as nv
 from pandas.errors import (
@@ -1059,7 +1059,7 @@ def _get_value(self, label, takeable: bool = False):
             return self.iloc[loc]
 
     def __setitem__(self, key, value) -> None:
-        if not PYPY and sys.version_info < (3, 14):
+        if not PYPY and not WARNING_CHECK_BROKEN:
             if sys.getrefcount(self) <= REF_COUNT + 1:
                 warnings.warn(
                     _chained_assignment_msg, ChainedAssignmentError, stacklevel=2
@@ -3338,7 +3338,7 @@ def update(self, other: Series | Sequence | Mapping) -> None:
         2    3
         dtype: int64
         """
-        if not PYPY and sys.version_info < (3, 14):
+        if not PYPY and not WARNING_CHECK_BROKEN:
             if sys.getrefcount(self) <= REF_COUNT:
                 warnings.warn(
                     _chained_assignment_method_msg,

From d8e15e3670dc74b0908377e0c1b94dfd84161c87 Mon Sep 17 00:00:00 2001
From: Nathan Goldbaum <nathan.goldbaum@gmail.com>
Date: Thu, 7 Aug 2025 14:46:23 -0600
Subject: [PATCH 05/12] TST: disable checks for ChainedAssignmentError in tests

---
 pandas/_testing/contexts.py | 4 ++--
 pandas/compat/__init__.py   | 4 ++++
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/pandas/_testing/contexts.py b/pandas/_testing/contexts.py
index da147c117ad43..37d631ea2fa0f 100644
--- a/pandas/_testing/contexts.py
+++ b/pandas/_testing/contexts.py
@@ -12,7 +12,7 @@
 )
 import uuid
 
-from pandas.compat import PYPY
+from pandas.compat import PYPY, WARNING_CHECK_BROKEN
 from pandas.errors import ChainedAssignmentError
 
 from pandas.io.common import get_handle
@@ -163,7 +163,7 @@ def with_csv_dialect(name: str, **kwargs) -> Generator[None]:
 def raises_chained_assignment_error(extra_warnings=(), extra_match=()):
     from pandas._testing import assert_produces_warning
 
-    if PYPY:
+    if PYPY or WARNING_CHECK_BROKEN:
         if not extra_warnings:
             from contextlib import nullcontext
 
diff --git a/pandas/compat/__init__.py b/pandas/compat/__init__.py
index d5dbcb74d29e4..9ccf20f6f8640 100644
--- a/pandas/compat/__init__.py
+++ b/pandas/compat/__init__.py
@@ -20,8 +20,10 @@
     ISMUSL,
     PY311,
     PY312,
+    PY314,
     PYPY,
     WASM,
+    WARNING_CHECK_BROKEN,
 )
 from pandas.compat.numpy import is_numpy_dev
 from pandas.compat.pyarrow import (
@@ -157,7 +159,9 @@ def is_ci_environment() -> bool:
     "ISMUSL",
     "PY311",
     "PY312",
+    "PY314",
     "PYPY",
+    "WARNING_CHECK_BROKEN",
     "WASM",
     "is_numpy_dev",
     "pa_version_under12p1",

From a1a5a6bf8283b2597f9cdc11f117ca552fa0a233 Mon Sep 17 00:00:00 2001
From: Nathan Goldbaum <nathan.goldbaum@gmail.com>
Date: Thu, 7 Aug 2025 14:49:37 -0600
Subject: [PATCH 06/12] MNT: appease isort

---
 pandas/_testing/contexts.py | 5 ++++-
 pandas/compat/__init__.py   | 2 +-
 pandas/core/frame.py        | 5 ++++-
 pandas/core/generic.py      | 5 ++++-
 pandas/core/indexing.py     | 5 ++++-
 pandas/core/series.py       | 5 ++++-
 6 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/pandas/_testing/contexts.py b/pandas/_testing/contexts.py
index 37d631ea2fa0f..b79cd797a3707 100644
--- a/pandas/_testing/contexts.py
+++ b/pandas/_testing/contexts.py
@@ -12,7 +12,10 @@
 )
 import uuid
 
-from pandas.compat import PYPY, WARNING_CHECK_BROKEN
+from pandas.compat import (
+    PYPY,
+    WARNING_CHECK_BROKEN,
+)
 from pandas.errors import ChainedAssignmentError
 
 from pandas.io.common import get_handle
diff --git a/pandas/compat/__init__.py b/pandas/compat/__init__.py
index 9ccf20f6f8640..be614c249fe87 100644
--- a/pandas/compat/__init__.py
+++ b/pandas/compat/__init__.py
@@ -22,8 +22,8 @@
     PY312,
     PY314,
     PYPY,
-    WASM,
     WARNING_CHECK_BROKEN,
+    WASM,
 )
 from pandas.compat.numpy import is_numpy_dev
 from pandas.compat.pyarrow import (
diff --git a/pandas/core/frame.py b/pandas/core/frame.py
index 6cf99e9f6279a..3f1b8517fcc7f 100644
--- a/pandas/core/frame.py
+++ b/pandas/core/frame.py
@@ -49,7 +49,10 @@
 from pandas._libs.hashtable import duplicated
 from pandas._libs.lib import is_range_indexer
 from pandas.compat import PYPY
-from pandas.compat._constants import REF_COUNT, WARNING_CHECK_BROKEN
+from pandas.compat._constants import (
+    REF_COUNT,
+    WARNING_CHECK_BROKEN,
+)
 from pandas.compat._optional import import_optional_dependency
 from pandas.compat.numpy import function as nv
 from pandas.errors import (
diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 0768e3048238d..89c58f2e5ccfd 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -83,7 +83,10 @@
     npt,
 )
 from pandas.compat import PYPY
-from pandas.compat._constants import REF_COUNT, WARNING_CHECK_BROKEN
+from pandas.compat._constants import (
+    REF_COUNT,
+    WARNING_CHECK_BROKEN,
+)
 from pandas.compat._optional import import_optional_dependency
 from pandas.compat.numpy import function as nv
 from pandas.errors import (
diff --git a/pandas/core/indexing.py b/pandas/core/indexing.py
index f6cb82c239edc..6a796c92977af 100644
--- a/pandas/core/indexing.py
+++ b/pandas/core/indexing.py
@@ -15,7 +15,10 @@
 from pandas._libs.indexing import NDFrameIndexerBase
 from pandas._libs.lib import item_from_zerodim
 from pandas.compat import PYPY
-from pandas.compat._constants import REF_COUNT, WARNING_CHECK_BROKEN
+from pandas.compat._constants import (
+    REF_COUNT,
+    WARNING_CHECK_BROKEN,
+)
 from pandas.errors import (
     AbstractMethodError,
     ChainedAssignmentError,
diff --git a/pandas/core/series.py b/pandas/core/series.py
index 2c7c7ca8ee11e..9242d47167f1c 100644
--- a/pandas/core/series.py
+++ b/pandas/core/series.py
@@ -34,7 +34,10 @@
 )
 from pandas._libs.lib import is_range_indexer
 from pandas.compat import PYPY
-from pandas.compat._constants import REF_COUNT, WARNING_CHECK_BROKEN
+from pandas.compat._constants import (
+    REF_COUNT,
+    WARNING_CHECK_BROKEN,
+)
 from pandas.compat._optional import import_optional_dependency
 from pandas.compat.numpy import function as nv
 from pandas.errors import (

From 979135fab05e6f6a3140561f8239ae27911d6f8c Mon Sep 17 00:00:00 2001
From: Nathan Goldbaum <nathan.goldbaum@gmail.com>
Date: Thu, 7 Aug 2025 15:13:36 -0600
Subject: [PATCH 07/12] BUG: fix WARNING_CHECK_BROKEN checks

---
 pandas/core/generic.py                           | 16 ++++++++--------
 .../test_chained_assignment_deprecation.py       |  3 +++
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 89c58f2e5ccfd..de3e506866341 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -7072,7 +7072,7 @@ def fillna(
         """
         inplace = validate_bool_kwarg(inplace, "inplace")
         if inplace:
-            if not PYPY and WARNING_CHECK_BROKEN:
+            if not PYPY and not WARNING_CHECK_BROKEN:
                 if sys.getrefcount(self) <= REF_COUNT:
                     warnings.warn(
                         _chained_assignment_method_msg,
@@ -7303,7 +7303,7 @@ def ffill(
         """
         inplace = validate_bool_kwarg(inplace, "inplace")
         if inplace:
-            if not PYPY and WARNING_CHECK_BROKEN:
+            if not PYPY and not WARNING_CHECK_BROKEN:
                 if sys.getrefcount(self) <= REF_COUNT:
                     warnings.warn(
                         _chained_assignment_method_msg,
@@ -7443,7 +7443,7 @@ def bfill(
         """
         inplace = validate_bool_kwarg(inplace, "inplace")
         if inplace:
-            if not PYPY and WARNING_CHECK_BROKEN:
+            if not PYPY and not WARNING_CHECK_BROKEN:
                 if sys.getrefcount(self) <= REF_COUNT:
                     warnings.warn(
                         _chained_assignment_method_msg,
@@ -7528,7 +7528,7 @@ def replace(
 
         inplace = validate_bool_kwarg(inplace, "inplace")
         if inplace:
-            if not PYPY and WARNING_CHECK_BROKEN:
+            if not PYPY and not WARNING_CHECK_BROKEN:
                 if sys.getrefcount(self) <= REF_COUNT:
                     warnings.warn(
                         _chained_assignment_method_msg,
@@ -7891,7 +7891,7 @@ def interpolate(
         inplace = validate_bool_kwarg(inplace, "inplace")
 
         if inplace:
-            if not PYPY and WARNING_CHECK_BROKEN:
+            if not PYPY and not WARNING_CHECK_BROKEN:
                 if sys.getrefcount(self) <= REF_COUNT:
                     warnings.warn(
                         _chained_assignment_method_msg,
@@ -8475,7 +8475,7 @@ def clip(
         inplace = validate_bool_kwarg(inplace, "inplace")
 
         if inplace:
-            if not PYPY and WARNING_CHECK_BROKEN:
+            if not PYPY and not WARNING_CHECK_BROKEN:
                 if sys.getrefcount(self) <= REF_COUNT:
                     warnings.warn(
                         _chained_assignment_method_msg,
@@ -10084,7 +10084,7 @@ def where(
         """
         inplace = validate_bool_kwarg(inplace, "inplace")
         if inplace:
-            if not PYPY and WARNING_CHECK_BROKEN:
+            if not PYPY and not WARNING_CHECK_BROKEN:
                 if sys.getrefcount(self) <= REF_COUNT:
                     warnings.warn(
                         _chained_assignment_method_msg,
@@ -10148,7 +10148,7 @@ def mask(
     ) -> Self | None:
         inplace = validate_bool_kwarg(inplace, "inplace")
         if inplace:
-            if not PYPY and WARNING_CHECK_BROKEN:
+            if not PYPY and not WARNING_CHECK_BROKEN:
                 if sys.getrefcount(self) <= REF_COUNT:
                     warnings.warn(
                         _chained_assignment_method_msg,
diff --git a/pandas/tests/copy_view/test_chained_assignment_deprecation.py b/pandas/tests/copy_view/test_chained_assignment_deprecation.py
index 4aef69a6fde98..8aa7696c9275e 100644
--- a/pandas/tests/copy_view/test_chained_assignment_deprecation.py
+++ b/pandas/tests/copy_view/test_chained_assignment_deprecation.py
@@ -1,6 +1,7 @@
 import numpy as np
 import pytest
 
+from pandas.compat import WARNING_CHECK_BROKEN
 from pandas.errors import ChainedAssignmentError
 
 from pandas import DataFrame
@@ -17,6 +18,8 @@ def test_series_setitem(indexer):
 
     # using custom check instead of tm.assert_produces_warning because that doesn't
     # fail if multiple warnings are raised
+    if WARNING_CHECK_BROKEN:
+        return
     with pytest.warns() as record:  # noqa: TID251
         df["a"][indexer] = 0
     assert len(record) == 1

From 180081b04fa9c18ebec787b1c40b321f93a0dce2 Mon Sep 17 00:00:00 2001
From: Nathan Goldbaum <nathan.goldbaum@gmail.com>
Date: Thu, 7 Aug 2025 16:20:02 -0600
Subject: [PATCH 08/12] MNT: handle changes in error messages in Python 3.14

---
 pandas/tests/indexes/test_indexing.py         |  9 ++++++-
 pandas/tests/io/parser/test_quoting.py        | 20 +++++++++++---
 pandas/tests/reshape/merge/test_merge.py      |  5 +++-
 pandas/tests/scalar/period/test_period.py     |  6 ++++-
 .../scalar/timestamp/test_constructors.py     | 16 +++++++++---
 pandas/tests/tools/test_to_datetime.py        | 26 +++++++++++++------
 6 files changed, 64 insertions(+), 18 deletions(-)

diff --git a/pandas/tests/indexes/test_indexing.py b/pandas/tests/indexes/test_indexing.py
index 1bbffcee3b671..c1c9f0fde863d 100644
--- a/pandas/tests/indexes/test_indexing.py
+++ b/pandas/tests/indexes/test_indexing.py
@@ -18,6 +18,7 @@
 import numpy as np
 import pytest
 
+from pandas.compat import PY314
 from pandas.errors import InvalidIndexError
 
 from pandas.core.dtypes.common import (
@@ -160,13 +161,19 @@ def test_contains_requires_hashable_raises(self, index):
         with pytest.raises(TypeError, match=msg):
             [] in index
 
+        if PY314:
+            container_or_iterable = "a container or iterable"
+        else:
+            container_or_iterable = "iterable"
+
         msg = "|".join(
             [
                 r"unhashable type: 'dict'",
                 r"must be real number, not dict",
                 r"an integer is required",
                 r"\{\}",
-                r"pandas\._libs\.interval\.IntervalTree' is not iterable",
+                r"pandas\._libs\.interval\.IntervalTree' is not "
+                f"{container_or_iterable}",
             ]
         )
         with pytest.raises(TypeError, match=msg):
diff --git a/pandas/tests/io/parser/test_quoting.py b/pandas/tests/io/parser/test_quoting.py
index a70b7e3389c1b..16381b4c2e42e 100644
--- a/pandas/tests/io/parser/test_quoting.py
+++ b/pandas/tests/io/parser/test_quoting.py
@@ -8,7 +8,7 @@
 
 import pytest
 
-from pandas.compat import PY311
+from pandas.compat import PY311, PY314
 from pandas.errors import ParserError
 
 from pandas import DataFrame
@@ -21,15 +21,23 @@
 skip_pyarrow = pytest.mark.usefixtures("pyarrow_skip")
 
 
+if PY314:
+    # TODO: write a regex that works with all new possitibilities here
+    MSG1 = ""
+    MSG2 = "[\s\S]*"
+else:
+    MSG1 = "a(n)? 1-character string"
+    MSG2 = "string( or None)?"
+
 @pytest.mark.parametrize(
     "kwargs,msg",
     [
-        ({"quotechar": "foo"}, '"quotechar" must be a(n)? 1-character string'),
+        ({"quotechar": "foo"}, f'"quotechar" must be {MSG1}'),
         (
             {"quotechar": None, "quoting": csv.QUOTE_MINIMAL},
             "quotechar must be set if quoting enabled",
         ),
-        ({"quotechar": 2}, '"quotechar" must be string( or None)?, not int'),
+        ({"quotechar": 2}, f'"quotechar" must be {MSG2}, not int'),
     ],
 )
 @skip_pyarrow  # ParserError: CSV parse error: Empty CSV file or block
@@ -88,8 +96,12 @@ def test_null_quote_char(all_parsers, quoting, quote_char):
 
     if quoting != csv.QUOTE_NONE:
         # Sanity checking.
+        if not PY314:
+            msg = "1-character string"
+        else:
+            msg = "unicode character or None"
         msg = (
-            '"quotechar" must be a 1-character string'
+            f'"quotechar" must be a {msg}'
             if PY311 and all_parsers.engine == "python" and quote_char == ""
             else "quotechar must be set if quoting enabled"
         )
diff --git a/pandas/tests/reshape/merge/test_merge.py b/pandas/tests/reshape/merge/test_merge.py
index a8e29ef03acc2..a5ea06399d09e 100644
--- a/pandas/tests/reshape/merge/test_merge.py
+++ b/pandas/tests/reshape/merge/test_merge.py
@@ -8,6 +8,7 @@
 import numpy as np
 import pytest
 
+from pandas.compat import PY314
 from pandas.core.dtypes.common import (
     is_object_dtype,
     is_string_dtype,
@@ -2420,10 +2421,12 @@ def test_merge_suffix_raises(suffixes):
         merge(a, b, left_index=True, right_index=True, suffixes=suffixes)
 
 
+TWO_GOT_THREE = "2, got 3" if PY314 else "2"
+
 @pytest.mark.parametrize(
     "col1, col2, suffixes, msg",
     [
-        ("a", "a", ("a", "b", "c"), r"too many values to unpack \(expected 2\)"),
+        ("a", "a", ("a", "b", "c"), fr"too many values to unpack \(expected {TWO_GOT_THREE}\)"),
         ("a", "a", tuple("a"), r"not enough values to unpack \(expected 2, got 1\)"),
     ],
 )
diff --git a/pandas/tests/scalar/period/test_period.py b/pandas/tests/scalar/period/test_period.py
index baaedaa853565..5de2a0780880b 100644
--- a/pandas/tests/scalar/period/test_period.py
+++ b/pandas/tests/scalar/period/test_period.py
@@ -8,6 +8,7 @@
 import numpy as np
 import pytest
 
+from pandas.compat import PY314
 from pandas._libs.tslibs import iNaT
 from pandas._libs.tslibs.ccalendar import (
     DAYS,
@@ -344,7 +345,10 @@ def test_invalid_arguments(self):
         msg = '^Given date string "-2000" not likely a datetime$'
         with pytest.raises(ValueError, match=msg):
             Period("-2000", "Y")
-        msg = "day is out of range for month"
+        if PY314:
+            msg = 'day 0 must be in range 1..31 for month 1 in year 1: 0'
+        else:
+            msg = "day is out of range for month"
         with pytest.raises(DateParseError, match=msg):
             Period("0", "Y")
         msg = "Unknown datetime string format, unable to parse"
diff --git a/pandas/tests/scalar/timestamp/test_constructors.py b/pandas/tests/scalar/timestamp/test_constructors.py
index 09ca5a71503ad..197d1c1fd6461 100644
--- a/pandas/tests/scalar/timestamp/test_constructors.py
+++ b/pandas/tests/scalar/timestamp/test_constructors.py
@@ -16,6 +16,7 @@
 import numpy as np
 import pytest
 
+from pandas.compat import PY314
 from pandas._libs.tslibs.dtypes import NpyDatetimeUnit
 from pandas.errors import OutOfBoundsDatetime
 
@@ -212,13 +213,19 @@ def test_constructor_positional(self):
         with pytest.raises(TypeError, match=msg):
             Timestamp(2000, 1)
 
-        msg = "month must be in 1..12"
+        if PY314:
+            msg = 'month must be in 1..12, not'
+        else:
+            msg = "day is out of range for month"
         with pytest.raises(ValueError, match=msg):
             Timestamp(2000, 0, 1)
         with pytest.raises(ValueError, match=msg):
             Timestamp(2000, 13, 1)
 
-        msg = "day is out of range for month"
+        if PY314:
+            msg = "must be in range 1..31 for month 1 in year 2000"
+        else:
+            msg = "day is out of range for month"
         with pytest.raises(ValueError, match=msg):
             Timestamp(2000, 1, 0)
         with pytest.raises(ValueError, match=msg):
@@ -242,7 +249,10 @@ def test_constructor_keyword(self):
         with pytest.raises(ValueError, match=msg):
             Timestamp(year=2000, month=13, day=1)
 
-        msg = "day is out of range for month"
+        if PY314:
+            msg = "must be in range 1..31 for month 1 in year 2000"
+        else:
+            msg = "day is out of range for month"
         with pytest.raises(ValueError, match=msg):
             Timestamp(year=2000, month=1, day=0)
         with pytest.raises(ValueError, match=msg):
diff --git a/pandas/tests/tools/test_to_datetime.py b/pandas/tests/tools/test_to_datetime.py
index 9bc88a7e0a824..85bb65ab4f12b 100644
--- a/pandas/tests/tools/test_to_datetime.py
+++ b/pandas/tests/tools/test_to_datetime.py
@@ -21,7 +21,7 @@
     iNaT,
     parsing,
 )
-from pandas.compat import WASM
+from pandas.compat import WASM, PY314
 from pandas.errors import (
     OutOfBoundsDatetime,
     OutOfBoundsTimedelta,
@@ -57,6 +57,13 @@
     r"alongside this."
 )
 
+if PY314:
+    NOT_99 = ", not 99"
+    DAY_IS_OUT_OF_RANGE = "day \d{1,2} must be in range 1\.\.\d{1,2} for month \d{1,2} in year \d{4}"
+else:
+    NOT_99 = ""
+    DAY_IS_OUT_OF_RANGE = "day is out of range for month"
+
 
 class TestTimeConversionFormats:
     def test_to_datetime_readonly(self, writable):
@@ -1372,7 +1379,7 @@ def test_datetime_invalid_scalar(self, value, format):
                 r'^Given date string "a" not likely a datetime$',
                 r'^unconverted data remains when parsing with format "%H:%M:%S": "9". '
                 f"{PARSING_ERR_MSG}$",
-                r"^second must be in 0..59: 00:01:99$",
+                fr"^second must be in 0..59{NOT_99}: 00:01:99$",
             ]
         )
         with pytest.raises(ValueError, match=msg):
@@ -1424,7 +1431,7 @@ def test_datetime_invalid_index(self, values, format):
                 f"{PARSING_ERR_MSG}$",
                 r'^unconverted data remains when parsing with format "%H:%M:%S": "9". '
                 f"{PARSING_ERR_MSG}$",
-                r"^second must be in 0..59: 00:01:99$",
+                fr"^second must be in 0..59{NOT_99}: 00:01:99$",
             ]
         )
         with pytest.raises(ValueError, match=msg):
@@ -2851,7 +2858,10 @@ def test_day_not_in_month_coerce(self, cache, arg, format):
         assert isna(to_datetime(arg, errors="coerce", format=format, cache=cache))
 
     def test_day_not_in_month_raise(self, cache):
-        msg = "day is out of range for month: 2015-02-29"
+        if PY314:
+            msg = "day 29 must be in range 1..28 for month 2 in year 2015: 2015-02-29"
+        else:
+            msg = "day is out of range for month: 2015-02-29"
         with pytest.raises(ValueError, match=msg):
             to_datetime("2015-02-29", errors="raise", cache=cache)
 
@@ -2861,12 +2871,12 @@ def test_day_not_in_month_raise(self, cache):
             (
                 "2015-02-29",
                 "%Y-%m-%d",
-                f"^day is out of range for month. {PARSING_ERR_MSG}$",
+                f"^{DAY_IS_OUT_OF_RANGE}. {PARSING_ERR_MSG}$",
             ),
             (
                 "2015-29-02",
                 "%Y-%d-%m",
-                f"^day is out of range for month. {PARSING_ERR_MSG}$",
+                f"^{DAY_IS_OUT_OF_RANGE}. {PARSING_ERR_MSG}$",
             ),
             (
                 "2015-02-32",
@@ -2883,12 +2893,12 @@ def test_day_not_in_month_raise(self, cache):
             (
                 "2015-04-31",
                 "%Y-%m-%d",
-                f"^day is out of range for month. {PARSING_ERR_MSG}$",
+                f"^{DAY_IS_OUT_OF_RANGE}. {PARSING_ERR_MSG}$",
             ),
             (
                 "2015-31-04",
                 "%Y-%d-%m",
-                f"^day is out of range for month. {PARSING_ERR_MSG}$",
+                f"^{DAY_IS_OUT_OF_RANGE}. {PARSING_ERR_MSG}$",
             ),
         ],
     )

From a1b9a55a006f98f387d834365d3a076b95785027 Mon Sep 17 00:00:00 2001
From: Nathan Goldbaum <nathan.goldbaum@gmail.com>
Date: Thu, 7 Aug 2025 16:20:12 -0600
Subject: [PATCH 09/12] MNT: migrate from codecs.open to open

---
 pandas/tests/io/formats/test_to_latex.py | 4 ++--
 pandas/tests/io/test_common.py           | 4 ++--
 pandas/util/_print_versions.py           | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/pandas/tests/io/formats/test_to_latex.py b/pandas/tests/io/formats/test_to_latex.py
index ebc6ff5be108f..e67fda3a75ba7 100644
--- a/pandas/tests/io/formats/test_to_latex.py
+++ b/pandas/tests/io/formats/test_to_latex.py
@@ -42,7 +42,7 @@ def test_to_latex_to_file_utf8_with_encoding(self):
         df = DataFrame([["au\xdfgangen"]])
         with tm.ensure_clean("test.tex") as path:
             df.to_latex(path, encoding="utf-8")
-            with codecs.open(path, "r", encoding="utf-8") as f:
+            with open(path, "r", encoding="utf-8") as f:
                 assert df.to_latex() == f.read()
 
     def test_to_latex_to_file_utf8_without_encoding(self):
@@ -50,7 +50,7 @@ def test_to_latex_to_file_utf8_without_encoding(self):
         df = DataFrame([["au\xdfgangen"]])
         with tm.ensure_clean("test.tex") as path:
             df.to_latex(path)
-            with codecs.open(path, "r", encoding="utf-8") as f:
+            with open(path, "r", encoding="utf-8") as f:
                 assert df.to_latex() == f.read()
 
     def test_to_latex_tabular_with_index(self):
diff --git a/pandas/tests/io/test_common.py b/pandas/tests/io/test_common.py
index 4a5e41397b59d..0d5e00dfdc245 100644
--- a/pandas/tests/io/test_common.py
+++ b/pandas/tests/io/test_common.py
@@ -523,9 +523,9 @@ def test_codecs_encoding(encoding, format):
         index=pd.Index([f"i-{i}" for i in range(30)]),
     )
     with tm.ensure_clean() as path:
-        with codecs.open(path, mode="w", encoding=encoding) as handle:
+        with open(path, mode="w", encoding=encoding) as handle:
             getattr(expected, f"to_{format}")(handle)
-        with codecs.open(path, mode="r", encoding=encoding) as handle:
+        with open(path, mode="r", encoding=encoding) as handle:
             if format == "csv":
                 df = pd.read_csv(handle, index_col=0)
             else:
diff --git a/pandas/util/_print_versions.py b/pandas/util/_print_versions.py
index bd20660bdbba6..3abe723a2b558 100644
--- a/pandas/util/_print_versions.py
+++ b/pandas/util/_print_versions.py
@@ -143,7 +143,7 @@ def show_versions(as_json: str | bool = False) -> None:
             sys.stdout.writelines(json.dumps(j, indent=2))
         else:
             assert isinstance(as_json, str)  # needed for mypy
-            with codecs.open(as_json, "wb", encoding="utf8") as f:
+            with open(as_json, "w", encoding="utf-8") as f:
                 json.dump(j, f, indent=2)
 
     else:

From 9bd7bbb734e10a39cced6613d48211b9578071e6 Mon Sep 17 00:00:00 2001
From: Nathan Goldbaum <nathan.goldbaum@gmail.com>
Date: Thu, 7 Aug 2025 16:49:17 -0600
Subject: [PATCH 10/12] MNT: fix linters

---
 pandas/tests/frame/test_query_eval.py              | 4 ++--
 pandas/tests/io/formats/test_to_latex.py           | 1 -
 pandas/tests/io/parser/test_quoting.py             | 7 +++++--
 pandas/tests/reshape/merge/test_merge.py           | 4 +++-
 pandas/tests/scalar/period/test_period.py          | 4 ++--
 pandas/tests/scalar/timestamp/test_constructors.py | 4 ++--
 pandas/tests/tools/test_to_datetime.py             | 8 ++++++--
 pandas/util/_print_versions.py                     | 1 -
 8 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/pandas/tests/frame/test_query_eval.py b/pandas/tests/frame/test_query_eval.py
index f93105498ac79..b599be5d042fe 100644
--- a/pandas/tests/frame/test_query_eval.py
+++ b/pandas/tests/frame/test_query_eval.py
@@ -168,7 +168,7 @@ def test_query_duplicate_column_name(self, engine, parser):
             }
         ).rename(columns={"B": "A"})
 
-        res = df.query('C == 1', engine=engine, parser=parser)
+        res = df.query("C == 1", engine=engine, parser=parser)
 
         expect = DataFrame(
             [[1, 1, 1]],
@@ -1411,7 +1411,7 @@ def test_expr_with_column_name_with_backtick_and_hash(self):
     def test_expr_with_column_name_with_backtick(self):
         # GH 59285
         df = DataFrame({"a`b": (1, 2, 3), "ab": (4, 5, 6)})
-        result = df.query("`a``b` < 2")  # noqa
+        result = df.query("`a``b` < 2")
         # Note: Formatting checks may wrongly consider the above ``inline code``.
         expected = df[df["a`b"] < 2]
         tm.assert_frame_equal(result, expected)
diff --git a/pandas/tests/io/formats/test_to_latex.py b/pandas/tests/io/formats/test_to_latex.py
index e67fda3a75ba7..75dd47f042a95 100644
--- a/pandas/tests/io/formats/test_to_latex.py
+++ b/pandas/tests/io/formats/test_to_latex.py
@@ -1,4 +1,3 @@
-import codecs
 from datetime import datetime
 from textwrap import dedent
 
diff --git a/pandas/tests/io/parser/test_quoting.py b/pandas/tests/io/parser/test_quoting.py
index 16381b4c2e42e..3485817f1ce59 100644
--- a/pandas/tests/io/parser/test_quoting.py
+++ b/pandas/tests/io/parser/test_quoting.py
@@ -8,7 +8,10 @@
 
 import pytest
 
-from pandas.compat import PY311, PY314
+from pandas.compat import (
+    PY311,
+    PY314,
+)
 from pandas.errors import ParserError
 
 from pandas import DataFrame
@@ -24,7 +27,7 @@
 if PY314:
     # TODO: write a regex that works with all new possitibilities here
     MSG1 = ""
-    MSG2 = "[\s\S]*"
+    MSG2 = r"[\s\S]*"
 else:
     MSG1 = "a(n)? 1-character string"
     MSG2 = "string( or None)?"
diff --git a/pandas/tests/reshape/merge/test_merge.py b/pandas/tests/reshape/merge/test_merge.py
index a5ea06399d09e..bcc8ef14ad6f3 100644
--- a/pandas/tests/reshape/merge/test_merge.py
+++ b/pandas/tests/reshape/merge/test_merge.py
@@ -9,6 +9,7 @@
 import pytest
 
 from pandas.compat import PY314
+
 from pandas.core.dtypes.common import (
     is_object_dtype,
     is_string_dtype,
@@ -2426,7 +2427,8 @@ def test_merge_suffix_raises(suffixes):
 @pytest.mark.parametrize(
     "col1, col2, suffixes, msg",
     [
-        ("a", "a", ("a", "b", "c"), fr"too many values to unpack \(expected {TWO_GOT_THREE}\)"),
+        ("a", "a", ("a", "b", "c"), (
+            fr"too many values to unpack \(expected {TWO_GOT_THREE}\)")),
         ("a", "a", tuple("a"), r"not enough values to unpack \(expected 2, got 1\)"),
     ],
 )
diff --git a/pandas/tests/scalar/period/test_period.py b/pandas/tests/scalar/period/test_period.py
index 5de2a0780880b..d8404937dcf97 100644
--- a/pandas/tests/scalar/period/test_period.py
+++ b/pandas/tests/scalar/period/test_period.py
@@ -8,7 +8,6 @@
 import numpy as np
 import pytest
 
-from pandas.compat import PY314
 from pandas._libs.tslibs import iNaT
 from pandas._libs.tslibs.ccalendar import (
     DAYS,
@@ -17,6 +16,7 @@
 from pandas._libs.tslibs.np_datetime import OutOfBoundsDatetime
 from pandas._libs.tslibs.parsing import DateParseError
 from pandas._libs.tslibs.period import INVALID_FREQ_ERR_MSG
+from pandas.compat import PY314
 
 from pandas import (
     NaT,
@@ -346,7 +346,7 @@ def test_invalid_arguments(self):
         with pytest.raises(ValueError, match=msg):
             Period("-2000", "Y")
         if PY314:
-            msg = 'day 0 must be in range 1..31 for month 1 in year 1: 0'
+            msg = "day 0 must be in range 1..31 for month 1 in year 1: 0"
         else:
             msg = "day is out of range for month"
         with pytest.raises(DateParseError, match=msg):
diff --git a/pandas/tests/scalar/timestamp/test_constructors.py b/pandas/tests/scalar/timestamp/test_constructors.py
index 197d1c1fd6461..dcb5fb94511e9 100644
--- a/pandas/tests/scalar/timestamp/test_constructors.py
+++ b/pandas/tests/scalar/timestamp/test_constructors.py
@@ -16,8 +16,8 @@
 import numpy as np
 import pytest
 
-from pandas.compat import PY314
 from pandas._libs.tslibs.dtypes import NpyDatetimeUnit
+from pandas.compat import PY314
 from pandas.errors import OutOfBoundsDatetime
 
 from pandas import (
@@ -214,7 +214,7 @@ def test_constructor_positional(self):
             Timestamp(2000, 1)
 
         if PY314:
-            msg = 'month must be in 1..12, not'
+            msg = "month must be in 1..12, not"
         else:
             msg = "day is out of range for month"
         with pytest.raises(ValueError, match=msg):
diff --git a/pandas/tests/tools/test_to_datetime.py b/pandas/tests/tools/test_to_datetime.py
index 85bb65ab4f12b..8262ff6a52b99 100644
--- a/pandas/tests/tools/test_to_datetime.py
+++ b/pandas/tests/tools/test_to_datetime.py
@@ -21,7 +21,10 @@
     iNaT,
     parsing,
 )
-from pandas.compat import WASM, PY314
+from pandas.compat import (
+    PY314,
+    WASM,
+)
 from pandas.errors import (
     OutOfBoundsDatetime,
     OutOfBoundsTimedelta,
@@ -59,7 +62,8 @@
 
 if PY314:
     NOT_99 = ", not 99"
-    DAY_IS_OUT_OF_RANGE = "day \d{1,2} must be in range 1\.\.\d{1,2} for month \d{1,2} in year \d{4}"
+    DAY_IS_OUT_OF_RANGE = (r"day \d{1,2} must be in range 1\.\.\d{1,2} for "
+                           r"month \d{1,2} in year \d{4}")
 else:
     NOT_99 = ""
     DAY_IS_OUT_OF_RANGE = "day is out of range for month"
diff --git a/pandas/util/_print_versions.py b/pandas/util/_print_versions.py
index 3abe723a2b558..efcb50bf4345c 100644
--- a/pandas/util/_print_versions.py
+++ b/pandas/util/_print_versions.py
@@ -1,6 +1,5 @@
 from __future__ import annotations
 
-import codecs
 import json
 import locale
 import os

From da5dcabc493ec1cba1fd3d08ef7cee85573a666d Mon Sep 17 00:00:00 2001
From: Nathan Goldbaum <nathan.goldbaum@gmail.com>
Date: Thu, 7 Aug 2025 17:56:05 -0600
Subject: [PATCH 11/12] MNT: fix pre-commit

---
 pandas/tests/io/formats/test_to_latex.py |  4 ++--
 pandas/tests/io/parser/test_quoting.py   |  1 +
 pandas/tests/io/test_common.py           |  2 +-
 pandas/tests/reshape/merge/test_merge.py |  9 +++++++--
 pandas/tests/tools/test_to_datetime.py   | 10 ++++++----
 5 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/pandas/tests/io/formats/test_to_latex.py b/pandas/tests/io/formats/test_to_latex.py
index 75dd47f042a95..82f36c94801e3 100644
--- a/pandas/tests/io/formats/test_to_latex.py
+++ b/pandas/tests/io/formats/test_to_latex.py
@@ -41,7 +41,7 @@ def test_to_latex_to_file_utf8_with_encoding(self):
         df = DataFrame([["au\xdfgangen"]])
         with tm.ensure_clean("test.tex") as path:
             df.to_latex(path, encoding="utf-8")
-            with open(path, "r", encoding="utf-8") as f:
+            with open(path, encoding="utf-8") as f:
                 assert df.to_latex() == f.read()
 
     def test_to_latex_to_file_utf8_without_encoding(self):
@@ -49,7 +49,7 @@ def test_to_latex_to_file_utf8_without_encoding(self):
         df = DataFrame([["au\xdfgangen"]])
         with tm.ensure_clean("test.tex") as path:
             df.to_latex(path)
-            with open(path, "r", encoding="utf-8") as f:
+            with open(path, encoding="utf-8") as f:
                 assert df.to_latex() == f.read()
 
     def test_to_latex_tabular_with_index(self):
diff --git a/pandas/tests/io/parser/test_quoting.py b/pandas/tests/io/parser/test_quoting.py
index 3485817f1ce59..261003d94ddf0 100644
--- a/pandas/tests/io/parser/test_quoting.py
+++ b/pandas/tests/io/parser/test_quoting.py
@@ -32,6 +32,7 @@
     MSG1 = "a(n)? 1-character string"
     MSG2 = "string( or None)?"
 
+
 @pytest.mark.parametrize(
     "kwargs,msg",
     [
diff --git a/pandas/tests/io/test_common.py b/pandas/tests/io/test_common.py
index 0d5e00dfdc245..5ee82268a87d8 100644
--- a/pandas/tests/io/test_common.py
+++ b/pandas/tests/io/test_common.py
@@ -525,7 +525,7 @@ def test_codecs_encoding(encoding, format):
     with tm.ensure_clean() as path:
         with open(path, mode="w", encoding=encoding) as handle:
             getattr(expected, f"to_{format}")(handle)
-        with open(path, mode="r", encoding=encoding) as handle:
+        with open(path, encoding=encoding) as handle:
             if format == "csv":
                 df = pd.read_csv(handle, index_col=0)
             else:
diff --git a/pandas/tests/reshape/merge/test_merge.py b/pandas/tests/reshape/merge/test_merge.py
index bcc8ef14ad6f3..2d16c0fe452e0 100644
--- a/pandas/tests/reshape/merge/test_merge.py
+++ b/pandas/tests/reshape/merge/test_merge.py
@@ -2424,11 +2424,16 @@ def test_merge_suffix_raises(suffixes):
 
 TWO_GOT_THREE = "2, got 3" if PY314 else "2"
 
+
 @pytest.mark.parametrize(
     "col1, col2, suffixes, msg",
     [
-        ("a", "a", ("a", "b", "c"), (
-            fr"too many values to unpack \(expected {TWO_GOT_THREE}\)")),
+        (
+            "a",
+            "a",
+            ("a", "b", "c"),
+            (rf"too many values to unpack \(expected {TWO_GOT_THREE}\)"),
+        ),
         ("a", "a", tuple("a"), r"not enough values to unpack \(expected 2, got 1\)"),
     ],
 )
diff --git a/pandas/tests/tools/test_to_datetime.py b/pandas/tests/tools/test_to_datetime.py
index 8262ff6a52b99..3df686e2c6d1a 100644
--- a/pandas/tests/tools/test_to_datetime.py
+++ b/pandas/tests/tools/test_to_datetime.py
@@ -62,8 +62,10 @@
 
 if PY314:
     NOT_99 = ", not 99"
-    DAY_IS_OUT_OF_RANGE = (r"day \d{1,2} must be in range 1\.\.\d{1,2} for "
-                           r"month \d{1,2} in year \d{4}")
+    DAY_IS_OUT_OF_RANGE = (
+        r"day \d{1,2} must be in range 1\.\.\d{1,2} for "
+        r"month \d{1,2} in year \d{4}"
+    )
 else:
     NOT_99 = ""
     DAY_IS_OUT_OF_RANGE = "day is out of range for month"
@@ -1383,7 +1385,7 @@ def test_datetime_invalid_scalar(self, value, format):
                 r'^Given date string "a" not likely a datetime$',
                 r'^unconverted data remains when parsing with format "%H:%M:%S": "9". '
                 f"{PARSING_ERR_MSG}$",
-                fr"^second must be in 0..59{NOT_99}: 00:01:99$",
+                rf"^second must be in 0..59{NOT_99}: 00:01:99$",
             ]
         )
         with pytest.raises(ValueError, match=msg):
@@ -1435,7 +1437,7 @@ def test_datetime_invalid_index(self, values, format):
                 f"{PARSING_ERR_MSG}$",
                 r'^unconverted data remains when parsing with format "%H:%M:%S": "9". '
                 f"{PARSING_ERR_MSG}$",
-                fr"^second must be in 0..59{NOT_99}: 00:01:99$",
+                rf"^second must be in 0..59{NOT_99}: 00:01:99$",
             ]
         )
         with pytest.raises(ValueError, match=msg):

From c547b6b94009330f6a3db58e0e692b3fe4003680 Mon Sep 17 00:00:00 2001
From: Nathan Goldbaum <nathan.goldbaum@gmail.com>
Date: Thu, 7 Aug 2025 17:58:55 -0600
Subject: [PATCH 12/12] TST: avoid EncodingWarning

---
 pandas/tests/io/test_common.py | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/pandas/tests/io/test_common.py b/pandas/tests/io/test_common.py
index 5ee82268a87d8..9f373f30c1817 100644
--- a/pandas/tests/io/test_common.py
+++ b/pandas/tests/io/test_common.py
@@ -513,9 +513,8 @@ def test_is_fsspec_url_chained():
     assert not icom.is_fsspec_url("filecache::://pandas/test.csv")
 
 
-@pytest.mark.parametrize("encoding", [None, "utf-8"])
 @pytest.mark.parametrize("format", ["csv", "json"])
-def test_codecs_encoding(encoding, format):
+def test_codecs_encoding(format):
     # GH39247
     expected = pd.DataFrame(
         1.1 * np.arange(120).reshape((30, 4)),
@@ -523,9 +522,9 @@ def test_codecs_encoding(encoding, format):
         index=pd.Index([f"i-{i}" for i in range(30)]),
     )
     with tm.ensure_clean() as path:
-        with open(path, mode="w", encoding=encoding) as handle:
+        with open(path, mode="w", encoding="utf-8") as handle:
             getattr(expected, f"to_{format}")(handle)
-        with open(path, encoding=encoding) as handle:
+        with open(path, encoding='utf-8') as handle:
             if format == "csv":
                 df = pd.read_csv(handle, index_col=0)
             else: