deprecate py38 support

CHANGELOG.rst

@@ -4,6 +4,8 @@ Changelog
 1.15.0 (master)
 ---------------
 * Dropped support for Python 3.7.
+* Support for Python 3.8 has been deprecated and will be removed in the next
+  scheduled release.
 
 1.14.0 (2023-11-01)
 -------------------

pyproject.toml

@@ -97,6 +97,8 @@ disallow_untyped_defs = true
 filterwarnings = [
     "error",
     "ignore:CSR support in pyOpenSSL is deprecated:DeprecationWarning",
+    # We ignore our own warning about dropping Python 3.8 support.
+    "ignore:Python 3.8 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 (
@@ -73,3 +76,10 @@
     ComparableX509,
     ImmutableMap,
 )
+
+if sys.version_info[:2] == (3, 8):
+    warnings.warn(
+        "Python 3.8 support will be dropped in the next scheduled release of "
+        "josepy. Please upgrade your Python version.",
+        DeprecationWarning,
+    )

tests/init_test.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, 8), reason="requires Python 3.8")
+def test_warns() -> None:
+    with pytest.warns(DeprecationWarning, match=re.escape(r"Python 3.8 support")):
+        importlib.reload(josepy)
+
+
+@pytest.mark.skipif(sys.version_info[:2] == (3, 8), reason="requires Python != 3.8")
+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