In Distribution.from_name, require a non-empty string. Fixes python/c…

…python#93259.

importlib_metadata/__init__.py

@@ -548,15 +548,18 @@ def locate_file(self, path):
         """
 
     @classmethod
-    def from_name(cls, name):
+    def from_name(cls, name: str):
         """Return the Distribution for the given package name.
 
         :param name: The name of the distribution package to search for.
         :return: The Distribution instance (or subclass thereof) for the named
             package, if found.
         :raises PackageNotFoundError: When the named package's distribution
             metadata cannot be found.
+        :raises ValueError: When an invalid value is supplied for name.
         """
+        if not name:
+            raise ValueError("A distribution name is required.")
         for resolver in cls._discover_resolvers():
             dists = resolver(DistributionFinder.Context(name=name))
             dist = next(iter(dists), None)

tests/test_main.py

@@ -1,7 +1,6 @@
 import re
 import json
 import pickle
-import pytest
 import unittest
 import warnings
 import importlib
@@ -51,7 +50,6 @@ def test_new_style_classes(self):
         self.assertIsInstance(Distribution, type)
         self.assertIsInstance(MetadataPathFinder, type)
 
-    @pytest.mark.xfail(reason="Not implemented")
     @fixtures.parameterize(
         dict(name=None),
         dict(name=''),