merge with 3.3

Lib/test/test_importlib/test_api.py

@@ -4,6 +4,7 @@
 from importlib import machinery
 import sys
 from test import support
+import types
 import unittest
 
 
@@ -175,13 +176,15 @@ def test_no_frozen_importlib(self):
                                     machinery.FrozenImporter))
 
 
-def test_main():
-    from test.support import run_unittest
-    run_unittest(ImportModuleTests,
-                 FindLoaderTests,
-                 InvalidateCacheTests,
-                 FrozenImportlibTests)
+class StartupTests(unittest.TestCase):
+
+    def test_everyone_has___loader__(self):
+        # Issue #17098: all modules should have __loader__ defined.
+        for name, module in sys.modules.items():
+            if isinstance(module, types.ModuleType):
+                self.assertTrue(hasattr(module, '__loader__'),
+                        '{!r} lacks a __loader__ attribute'.format(name))
 
 
 if __name__ == '__main__':
-    test_main()
+    unittest.main()