Start testing Python 3.15 Alpha (boto#3628)

Add Python 3.15-dev to the GitHub Actions matrices for run-tests and run-crt-test to catch compatibility issues early without claiming official support.

Set PYO3_USE_ABI3_FORWARD_COMPATIBILITY=1 only for the 3.15-dev matrix jobs to avoid prerelease install failures from PyO3-based dependencies.

Update tests/unit/test_compress.py test helpers to pin compresslevel=9 (with mtime fixed) so gzip byte-for-byte fixtures stay stable across Python versions, including 3.15.

Author: jonathan343

.github/workflows/run-crt-test.yml

@@ -15,11 +15,14 @@ concurrency:
 jobs:
   build:
     runs-on: '${{ matrix.os }}'
+    continue-on-error: ${{ matrix.python-version == '3.15-dev' }}
     strategy:
       fail-fast: false
       matrix:
-        python-version: ['3.9', '3.10', '3.11', '3.12', '3.13', '3.14']
+        python-version: ['3.9', '3.10', '3.11', '3.12', '3.13', '3.14', '3.15-dev']
         os: [ubuntu-latest, macOS-latest, windows-latest]
+    env:
+      PYO3_USE_ABI3_FORWARD_COMPATIBILITY: ${{ matrix.python-version == '3.15-dev' && '1' || '' }}
 
     steps:
       - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3

.github/workflows/run-tests.yml

@@ -15,11 +15,14 @@ concurrency:
 jobs:
   build:
     runs-on: '${{ matrix.os }}'
+    continue-on-error: ${{ matrix.python-version == '3.15-dev' }}
     strategy:
       fail-fast: false
       matrix:
-        python-version: ['3.9', '3.10', '3.11', '3.12', '3.13', '3.14']
+        python-version: ['3.9', '3.10', '3.11', '3.12', '3.13', '3.14', '3.15-dev']
         os: [ubuntu-latest, macOS-latest, windows-latest]
+    env:
+      PYO3_USE_ABI3_FORWARD_COMPATIBILITY: ${{ matrix.python-version == '3.15-dev' && '1' || '' }}
 
     steps:
       - uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3

requirements-dev-lock.txt

@@ -311,9 +311,9 @@ tomli==2.2.1 \
     # via
     #   coverage
     #   pytest
-typing-extensions==4.13.2 \
-    --hash=sha256:a439e7c04b49fec3e5d3e2beaa21755cadbbdc391694e28ccdd36ca4a1408f8c \
-    --hash=sha256:e6c81219bd689f51865d9e372991c540bda33a0379d5573cddb9a3a23f7caaef
+typing-extensions==4.15.0 \
+    --hash=sha256:0cea48d173cc12fa28ecabc3b837ea3cf6f38c6d1136f85cbaaf598984861466 \
+    --hash=sha256:f0fa19c6845758ab08074a0cfa8b7aecb71c999ca73d62883bc25cc018c4e548
     # via
     #   exceptiongroup
     #   referencing

tests/unit/test_compress.py

@@ -107,11 +107,17 @@ def request_dict_non_seekable_bytes_stream():
 class StaticGzipFile(gzip.GzipFile):
     def __init__(self, *args, **kwargs):
         kwargs['mtime'] = 1
+        # Python 3.15 changed default gzip header output; pin level so these
+        # tests remain byte-stable across runtimes.
+        kwargs['compresslevel'] = 9
         super().__init__(*args, **kwargs)
 
 
 def static_compress(*args, **kwargs):
     kwargs['mtime'] = 1
+    # Python 3.15 changed default gzip header output; pin level so these
+    # tests remain byte-stable across runtimes.
+    kwargs['compresslevel'] = 9
     return gzip.compress(*args, **kwargs)