Validate metadata with packaging lib

pyproject.toml

@@ -40,6 +40,7 @@ dependencies = [
 	"keyring >= 15.1; platform_machine != 'ppc64le' and platform_machine != 's390x'",
 	"rfc3986 >= 1.4.0",
 	"rich >= 12.0.0",
+	"packaging >= 24.1",
 
 	# workaround for #1116
 	"pkginfo < 1.11",

tests/test_check.py

@@ -281,6 +281,80 @@ def test_main(monkeypatch):
     assert check_stub.calls == [pretend.call(["dist/*"], strict=False)]
 
 
+def test_fails_invalid_classifiers(tmp_path, capsys, caplog):
+    sdist = build_sdist(
+        tmp_path,
+        {
+            "setup.cfg": (
+                """
+                    [metadata]
+                    name = test-package
+                    version = 0.0.1
+                    long_description = file:README.md
+                    long_description_content_type = text/markdown
+                    classifiers =
+                        Framework | Django |  5
+                    """
+            ),
+            "README.md": (
+                """
+                # test-package
+
+                A test package.
+                """
+            ),
+        },
+    )
+
+    assert check.check([sdist])
+
+    assert capsys.readouterr().out == f"Checking {sdist}: FAILED\n"
+
+    assert len(caplog.record_tuples) > 0
+    assert caplog.record_tuples == [
+        (
+            "twine.commands.check",
+            logging.ERROR,
+            "`Framework | Django |  5` is not a valid classifier"
+            " and would prevent upload to PyPI.\n",
+        )
+    ]
+
+
+def test_passes_valid_classifiers(tmp_path, capsys, caplog):
+    sdist = build_sdist(
+        tmp_path,
+        {
+            "setup.cfg": (
+                """
+                    [metadata]
+                    name = test-package
+                    version = 0.0.1
+                    long_description = file:README.md
+                    long_description_content_type = text/markdown
+                    classifiers =
+                        Programming Language :: Python :: 3
+                        Framework :: Django
+                        Framework :: Django :: 5.1
+                    """
+            ),
+            "README.md": (
+                """
+                # test-package
+
+                A test package.
+                """
+            ),
+        },
+    )
+
+    assert not check.check([sdist])
+
+    assert capsys.readouterr().out == f"Checking {sdist}: PASSED\n"
+
+    assert caplog.record_tuples == []
+
+
 # TODO: Test print() color output
 
 # TODO: Test log formatting

twine/commands/check.py

@@ -105,6 +105,9 @@ def _check_file(
         if rendering_result is None:
             is_ok = False
 
+    # Will raise an exception if the metadata is invalid
+    package.metadata_obj()
+
     return warnings, is_ok
 
 

twine/package.py

@@ -21,6 +21,8 @@
 import sys
 from typing import Any, Dict, List, NamedTuple, Optional, Sequence, Tuple, Union, cast
 
+from packaging.metadata import Metadata as PackagingMetadata
+
 if sys.version_info >= (3, 10):
     import importlib.metadata as importlib_metadata
 else:
@@ -142,6 +144,49 @@ def from_filename(cls, filename: str, comment: Optional[str]) -> "PackageFile":
 
         return cls(filename, comment, meta, py_version, dtype)
 
+    def metadata_obj(self) -> PackagingMetadata:
+        meta = self.metadata
+        # TODO: this should probably take metadata_dictionary as base and modify
+        # it to remove the keys that aren't accepted by packaging.RawMetadata
+        data = {
+            # Metadata 1.0 - PEP 241
+            "metadata_version": meta.metadata_version,
+            "name": self.safe_name,
+            "version": meta.version,
+            "platforms": meta.supported_platforms,
+            "summary": meta.summary,
+            "description": meta.description,
+            "keywords": meta.keywords,
+            "home_page": meta.home_page,
+            "author": meta.author,
+            "author_email": meta.author_email,
+            "license": meta.license,
+            # Metadata 1.1 - PEP 314
+            "supported_platforms": meta.supported_platforms,
+            "download_url": meta.download_url,
+            "classifiers": meta.classifiers,
+            "requires": meta.requires,
+            "provides": meta.provides,
+            "obsoletes": meta.obsoletes,
+            # Metadata 1.2 - PEP 345
+            "maintainer": meta.maintainer,
+            "maintainer_email": meta.maintainer_email,
+            "requires_dist": meta.requires_dist,
+            "provides_dist": meta.provides_dist,
+            "obsoletes_dist": meta.obsoletes_dist,
+            "requires_python": meta.requires_python,
+            "requires_external": meta.requires_external,
+            "project_urls": meta.project_urls,
+            # Metadata 2.1 - PEP 566
+            "description_content_type": meta.description_content_type,
+            "provides_extra": meta.provides_extras,
+        }
+        if meta.metadata_version and meta.metadata_version > "2.1":
+            # Metadata 2.2 - PEP 643
+            data.update({"dynamic": meta.dynamic})
+
+        return PackagingMetadata.from_raw(data, validate=True)  # type: ignore[arg-type]
+
     def metadata_dictionary(self) -> Dict[str, MetadataValue]:
         """Merge multiple sources of metadata into a single dictionary.