deprecate python 3.9 support (#240)

Author: bmw

CHANGELOG.rst

@@ -4,6 +4,9 @@ Changelog
 2.2.0 (main)
 ------------
 
+* Support for Python 3.9 has been deprecated and will be removed in the next
+  scheduled release.
+
 2.1.0 (2025-07-08)
 ------------
 

pyproject.toml

@@ -96,6 +96,8 @@ disallow_untyped_defs = true
 [tool.pytest.ini_options]
 filterwarnings = [
     "error",
+    # We ignore our own warning about dropping Python 3.9 support.
+    "ignore:Python 3.9 support will be dropped:DeprecationWarning",
 ]
 norecursedirs = "*.egg .eggs dist build docs .tox"
 

src/josepy/__init__.py

@@ -26,6 +26,9 @@
 
 """
 
+import sys
+import warnings
+
 # flake8: noqa
 from josepy.b64 import b64decode, b64encode
 from josepy.errors import (
@@ -72,3 +75,10 @@
     ComparableRSAKey,
     ImmutableMap,
 )
+
+if sys.version_info[:2] == (3, 9):
+    warnings.warn(
+        "Python 3.9 support will be dropped in the next scheduled release of "
+        "josepy. Please upgrade your Python version.",
+        DeprecationWarning,
+    )

tests/init_tests.py

@@ -0,0 +1,25 @@
+import importlib
+import re
+import sys
+import warnings
+
+import pytest
+
+import josepy
+
+
+@pytest.mark.skipif(sys.version_info[:2] != (3, 9), reason="requires Python 3.9")
+def test_warns() -> None:
+    with pytest.warns(DeprecationWarning, match=re.escape(r"Python 3.9 support")):
+        importlib.reload(josepy)
+
+
+@pytest.mark.skipif(sys.version_info[:2] == (3, 9), reason="requires Python != 3.9")
+def test_does_not_warn() -> None:
+    with warnings.catch_warnings():
+        warnings.simplefilter("error")
+        importlib.reload(josepy)
+
+
+if __name__ == "__main__":
+    sys.exit(pytest.main(sys.argv[1:] + [__file__]))  # pragma: no cover