Add tests for Dynamic core metadata for setup.cfg

Author: abravalheri

setuptools/tests/test_core_metadata.py

@@ -8,6 +8,7 @@
 from email.message import EmailMessage, Message
 from email.parser import Parser
 from email.policy import EmailPolicy
+from inspect import cleandoc
 from pathlib import Path
 from unittest.mock import Mock
 
@@ -411,6 +412,72 @@ def test_equivalent_output(self, tmp_path, dist):
         _assert_roundtrip_message(pkg_info)
 
 
+class TestPEP643:
+    STATIC_CONFIG = {
+        "setup.cfg": cleandoc(
+            """
+            [metadata]
+            name = package
+            version = 0.0.1
+            author = Foo Bar
+            author_email = [email protected]
+            long_description = Long
+                               description
+            description = Short description
+            keywords = one, two
+            [options]
+            install_requires = requests
+            """
+        ),
+    }
+
+    @pytest.mark.parametrize("file", STATIC_CONFIG.keys())
+    def test_static_config_has_no_dynamic(self, file, tmpdir_cwd):
+        Path(file).write_text(self.STATIC_CONFIG[file], encoding="utf-8")
+        metadata = _get_metadata()
+        assert metadata.get_all("Dynamic") is None
+        assert metadata.get_all("dynamic") is None
+
+    @pytest.mark.parametrize("file", STATIC_CONFIG.keys())
+    @pytest.mark.parametrize(
+        "fields",
+        [
+            # Single dynamic field
+            {"requires-python": ("python_requires", ">=3.12")},
+            {"author-email": ("author_email", "[email protected]")},
+            {"keywords": ("keywords", ["hello", "world"])},
+            # Multiple dynamic fields
+            {
+                "summary": ("description", "hello world"),
+                "description": ("long_description", "bla bla bla bla"),
+                "requires-dist": ("install_requires", ["hello-world"]),
+            },
+        ],
+    )
+    def test_modified_fields_marked_as_dynamic(self, file, fields, tmpdir_cwd):
+        # We start with a static config
+        Path(file).write_text(self.STATIC_CONFIG[file], encoding="utf-8")
+        dist = _makedist()
+
+        # ... but then we simulate the effects of a plugin modifying the distribution
+        for attr, value in fields.values():
+            # `dist` and `dist.metadata` are complicated...
+            # Some attributes work when set on `dist`, others on `dist.metadata`...
+            # Here we set in both just in case (this also avoids calling `_finalize_*`)
+            setattr(dist, attr, value)
+            setattr(dist.metadata, attr, value)
+
+        # Then we should be able to list the modified fields as Dynamic
+        metadata = _get_metadata(dist)
+        assert set(metadata.get_all("Dynamic")) == set(fields)
+
+
+def _makedist(**attrs):
+    dist = Distribution(attrs)
+    dist.parse_config_files()
+    return dist
+
+
 def _assert_roundtrip_message(metadata: str) -> None:
     """Emulate the way wheel.bdist_wheel parses and regenerates the message,
     then ensures the metadata generated by setuptools is compatible.
@@ -482,6 +549,10 @@ def _get_pkginfo(dist: Distribution):
         return fp.getvalue()
 
 
+def _get_metadata(dist: Distribution | None = None):
+    return message_from_string(_get_pkginfo(dist or _makedist()))
+
+
 def _valid_metadata(text: str) -> bool:
     metadata = Metadata.from_email(text, validate=True)  # can raise exceptions
     return metadata is not None