Fix compatibility kludge to work with older packaging

.github/workflows/main.yml

@@ -48,6 +48,13 @@ jobs:
           - ubuntu-latest
           - macos-latest
           - windows-latest
+        tox-environment:
+          - py
+        include:
+          # Test with the oldest supported ``packaging`` version.
+          - platform: ubuntu-latest
+            python-version: "3.8"
+            tox-environment: py-packaging240
     runs-on: ${{ matrix.platform }}
     steps:
       - uses: actions/checkout@v4.2.2
@@ -59,7 +66,7 @@ jobs:
       - name: Run type-checking
         run: python -m tox -e types
       - name: Run tests
-        run: python -m tox -e py
+        run: python -m tox -e ${{ matrix.tox-environment }}
 
   # Because the tests can be flaky, they shouldn't be required for merge, but
   # it's still helpful to run them on PRs. See:

changelog/1217.bugfix.rst

@@ -0,0 +1,2 @@
+Fix compatibility kludge for invalid License-File metadata entries emitted by
+build backends to work also with ``packaging`` version 24.0.

tests/fixtures/everything.metadata23

@@ -0,0 +1,41 @@
+Metadata-Version: 2.3
+Name: BeagleVote
+Version: 1.0a2
+Platform: ObscureUnix
+Platform: RareDOS
+Supported-Platform: RedHat 7.2
+Supported-Platform: i386-win32-2791
+Summary: A module for collecting votes from beagles.
+Description-Content-Type: text/markdown; charset=UTF-8; variant=GFM
+Keywords: dog,puppy,voting,election
+Home-page: http://www.example.com/~cschultz/bvote/
+Download-URL: …/BeagleVote-0.45.tgz
+Author: C. Schultz, Universal Features Syndicate,
+        Los Angeles, CA <cschultz@peanuts.example.com>
+Author-email: "C. Schultz" <cschultz@example.com>
+Maintainer: C. Schultz, Universal Features Syndicate,
+        Los Angeles, CA <cschultz@peanuts.example.com>
+Maintainer-email: "C. Schultz" <cschultz@example.com>
+License: This software may only be obtained by sending the
+        author a postcard, and then the user promises not
+        to redistribute it.
+Classifier: Development Status :: 4 - Beta
+Classifier: Environment :: Console (Text Based)
+Provides-Extra: pdf
+Requires-Dist: reportlab; extra == 'pdf'
+Requires-Dist: pkginfo
+Requires-Dist: PasteDeploy
+Requires-Dist: zope.interface (>3.5.0)
+Requires-Dist: pywin32 >1.0; sys_platform == 'win32'
+Requires-Python: >=3
+Requires-External: C
+Requires-External: libpng (>=1.5)
+Requires-External: make; sys_platform != "win32"
+Project-URL: Bug Tracker, http://bitbucket.org/tarek/distribute/issues/
+Project-URL: Documentation, https://example.com/BeagleVote
+Provides-Dist: OtherProject
+Provides-Dist: AnotherProject (3.4)
+Provides-Dist: virtual_package; python_version >= "3.4"
+Dynamic: Obsoletes-Dist
+
+This description intentionally left blank.

tests/test_package.py

@@ -14,9 +14,11 @@
 import json
 import string
 
+import packaging
 import pretend
 import pytest
 from packaging import metadata
+from packaging import version
 
 from twine import exceptions
 from twine import package as package_file
@@ -175,6 +177,10 @@ def test_package_safe_name_is_correct(pkg_name, expected_name):
 def test_metadata_keys_consistency():
     """Check that the translation keys exist in the respective ``TypedDict``."""
     raw_keys = metadata.RawMetadata.__annotations__.keys()
+    if version.Version(packaging.__version__) < version.Version("24.1"):
+        # ``packaging`` version 24.0 and earlier do not know about the
+        # License-Expression and License-File metadata fields yet.
+        raw_keys = raw_keys | set(("license_files", "license_expression"))
     assert set(package_file._RAW_TO_PACKAGE_METADATA.keys()).issubset(raw_keys)
     package_keys = package_file.PackageMetadata.__annotations__.keys()
     assert set(package_file._RAW_TO_PACKAGE_METADATA.values()).issubset(package_keys)
@@ -434,32 +440,37 @@ def test_package_from_unrecognized_file_error():
     assert "Unknown distribution format" in err.value.args[0]
 
 
-@pytest.mark.parametrize(
-    "read_data, filtered",
-    [
-        pytest.param(
-            "Metadata-Version: 2.1\n"
-            "Name: test-package\n"
-            "Version: 1.0.0\n"
-            "License-File: LICENSE\n",
-            True,
-            id="invalid License-File",
-        ),
-        pytest.param(
-            "Metadata-Version: 2.4\n"
-            "Name: test-package\n"
-            "Version: 1.0.0\n"
-            "License-File: LICENSE\n",
-            False,
-            id="valid License-File",
-        ),
-    ],
-)
-def test_setuptools_license_file(read_data, filtered, monkeypatch):
+def test_setuptools_license_file_invalid(monkeypatch):
     """Drop License-File metadata entries if Metadata-Version is less than 2.4."""
+    read_data = (
+        "Metadata-Version: 2.1\n"
+        "Name: test-package\n"
+        "Version: 1.0.0\n"
+        "License-File: LICENSE\n"
+    )
+    monkeypatch.setattr(package_file.wheel.Wheel, "read", lambda _: read_data)
+    filename = "tests/fixtures/twine-1.5.0-py2.py3-none-any.whl"
+
+    package = package_file.PackageFile.from_filename(filename, comment=None)
+    meta = package.metadata_dictionary()
+    assert "license_file" not in meta
+
+
+@pytest.mark.skipif(
+    version.Version(packaging.__version__) < version.Version("24.1"),
+    reason="packaging is too old",
+)
+def test_setuptools_license_file_valid(monkeypatch):
+    """License-File metadata entries are kept when Metadata-Version is 2.4."""
+    read_data = (
+        "Metadata-Version: 2.4\n"
+        "Name: test-package\n"
+        "Version: 1.0.0\n"
+        "License-File: LICENSE\n"
+    )
     monkeypatch.setattr(package_file.wheel.Wheel, "read", lambda _: read_data)
     filename = "tests/fixtures/twine-1.5.0-py2.py3-none-any.whl"
 
     package = package_file.PackageFile.from_filename(filename, comment=None)
     meta = package.metadata_dictionary()
-    assert filtered != ("license_file" in meta)
+    assert "license_file" in meta

tests/test_repository.py

@@ -14,9 +14,11 @@
 import logging
 from contextlib import contextmanager
 
+import packaging
 import pretend
 import pytest
 import requests
+from packaging import version
 
 from twine import package
 from twine import repository
@@ -61,8 +63,12 @@ def test_iterables_are_flattened():
 
 def test_all_metadata_fields_are_flattened(monkeypatch):
     """Verify that package metadata fields are correctly flattened."""
-    # This file contains all metadata fields known up to metadata version 2.4.
-    metadata = open("tests/fixtures/everything.metadata")
+    if version.Version(packaging.__version__) < version.Version("24.1"):
+        # All metadata fields up to metadata version 2.3
+        metadata = open("tests/fixtures/everything.metadata23")
+    else:
+        # All metadata fields up to metadata version 2.4
+        metadata = open("tests/fixtures/everything.metadata24")
     monkeypatch.setattr(package.wheel.Wheel, "read", metadata.read)
     filename = "tests/fixtures/twine-1.5.0-py2.py3-none-any.whl"
     data = package.PackageFile.from_filename(

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 minversion = 3.8
-envlist = lint,types,py{38,39,310,311,312,313},integration,docs
+envlist = lint,types,py{38,39,310,311,312,313}{,-packaging240},integration,docs
 isolated_build = True
 
 [testenv]
@@ -9,6 +9,7 @@ deps =
     pytest
     pytest-socket
     coverage
+    packaging240: packaging==24.0
 passenv =
     PYTEST_ADDOPTS
 setenv =

twine/package.py

@@ -214,14 +214,7 @@ def from_filename(cls, filename: str, comment: Optional[str]) -> "PackageFile":
 
         # Parse and validate metadata.
         meta, unparsed = metadata.parse_email(data)
-        if unparsed:
-            raise exceptions.InvalidDistribution(
-                "Invalid distribution metadata: {}".format(
-                    "; ".join(
-                        f"unrecognized or malformed field {key!r}" for key in unparsed
-                    )
-                )
-            )
+
         # setuptools emits License-File metadata fields while declaring
         # Metadata-Version 2.1. This is invalid because the metadata
         # specification does not allow to add arbitrary fields, and because
@@ -232,6 +225,22 @@ def from_filename(cls, filename: str, comment: Optional[str]) -> "PackageFile":
         # than 2.4.
         if version.Version(meta.get("metadata_version", "0")) < version.Version("2.4"):
             meta.pop("license_files", None)
+            # Support for metadata version 2.4 requires packaging version 24.1
+            # or later. When parsing metadata with an older packaging, the
+            # invalid License-File fields are not understood and added to the
+            # unparsed dictionary. Remove them to avoid triggering the
+            # following check.
+            unparsed.pop("license-file", None)
+
+        if unparsed:
+            raise exceptions.InvalidDistribution(
+                "Invalid distribution metadata: {}".format(
+                    "; ".join(
+                        f"unrecognized or malformed field {key!r}" for key in unparsed
+                    )
+                )
+            )
+
         try:
             metadata.Metadata.from_raw(meta)
         except metadata.ExceptionGroup as group: