Relax assertion that all names in packages_distributions are identifi…

…ers.

The main contstraint here for an importable module is that it must not contain a module separator ('.'). Other names that contain dashes or spaces cannot be imported with the 'import' statement, but can be imported with 'importlib.import_module' or invoked with 'runpy'.

tests/test_main.py

@@ -354,7 +354,9 @@ def test_packages_distributions_all_module_types(self):
             assert distributions[f'in_namespace_{i}'] == ['all_distributions']
             assert distributions[f'in_package_{i}'] == ['all_distributions']
 
-        # All keys return from packages_distributions() should be valid
-        # import names, which means that they must _at least_ be valid
-        # identifiers:
-        assert all(import_name.isidentifier() for import_name in distributions.keys())
+        def is_importable(name):
+            return '.' not in name
+
+        # All keys returned from packages_distributions() should be
+        # importable.
+        assert all(map(is_importable, distributions))