Add tests asserting that protocols match stdlib also.

Author: jaraco

importlib_metadata/_meta.py

@@ -7,11 +7,13 @@
     Protocol,
     TypeVar,
     overload,
+    runtime_checkable,
 )
 
 _T = TypeVar("_T")
 
 
+@runtime_checkable
 class PackageMetadata(Protocol):
     def __len__(self) -> int: ...  # pragma: no cover
 
@@ -71,6 +73,7 @@ def read_bytes(self) -> bytes: ...  # pragma: no cover
     def exists(self) -> bool: ...  # pragma: no cover
 
 
+@runtime_checkable
 class IPackagePath(Protocol):
     hash: Any | None
     size: int | None
@@ -88,6 +91,7 @@ def parts(self) -> tuple[str, ...]: ...  # pragma: no cover
     def __fspath__(self) -> str: ...  # pragma: no cover
 
 
+@runtime_checkable
 class IDistribution(Protocol):
     def read_text(
         self, filename: str | os.PathLike[str]

tests/test_protocols.py

@@ -0,0 +1,36 @@
+from __future__ import annotations
+
+import importlib.metadata as stdlib
+import pathlib
+import tempfile
+import unittest
+
+from importlib_metadata import IDistribution, IPackagePath, PackageMetadata
+
+
+class ProtocolTests(unittest.TestCase):
+    def setUp(self):
+        self.tmpdir = tempfile.TemporaryDirectory()
+        self.addCleanup(self.tmpdir.cleanup)
+        tmp_path = pathlib.Path(self.tmpdir.name)
+        dist_info = tmp_path / 'protocol_sample-1.0.dist-info'
+        dist_info.mkdir()
+        (dist_info / 'METADATA').write_text(
+            'Name: protocol-sample\nVersion: 1.0\n', encoding='utf-8'
+        )
+        self.dist = stdlib.PathDistribution(dist_info)
+
+    def test_stdlib_distribution_matches_protocol(self):
+        assert isinstance(self.dist, IDistribution)
+
+    def test_stdlib_metadata_matches_protocol(self):
+        meta = self.dist.metadata
+        assert meta is not None
+        assert isinstance(meta, PackageMetadata)
+
+    def test_stdlib_package_path_matches_protocol(self):
+        package_path = stdlib.PackagePath('protocol_sample/__init__.py')
+        package_path.hash = None
+        package_path.size = 0
+        package_path.dist = self.dist
+        assert isinstance(package_path, IPackagePath)