Add test ensuring MetadataPathFinder._search_paths is available for P…

…yPA projects. Fixes #111.

CHANGES.rst

@@ -4,6 +4,9 @@ v3.4.0
 * #10: Project now declares itself as being typed.
 * #272: Additional performance enhancements to distribution
   discovery.
+* #111: For PyPA projects, add test ensuring that
+  ``MetadataPathFinder._search_paths`` honors the needed
+  interface. Method is still private.
 
 v3.3.0
 ======

tests/test_integration.py

@@ -5,6 +5,7 @@
 from . import fixtures
 from importlib_metadata import (
     Distribution,
+    MetadataPathFinder,
     _compat,
     version,
 )
@@ -47,3 +48,14 @@ def test_find_local(self):
         dist = Distribution._local()
         assert dist.metadata['Name'] == 'local-pkg'
         assert dist.version == '2.0.1'
+
+
+class DistSearch(unittest.TestCase):
+    def test_search_dist_dirs(self):
+        """
+        Pip needs the _search_paths interface to locate
+        distribution metadata dirs. Protect it for PyPA
+        use-cases (only). Ref python/importlib_metadata#111.
+        """
+        res = MetadataPathFinder._search_paths('any-name', [])
+        assert list(res) == []