- Add new Warning class, ImportWarning

 - Warn-raise ImportWarning when importing would have picked up a directory
   as package, if only it'd had an __init__.py. This swaps two tests (for
   case-ness and __init__-ness), but case-test is not really more expensive,
   and it's not in a speed-critical section.

 - Test for the new warning by importing a common non-package directory on
   sys.path: site-packages

 - In regrtest.py, silence warnings generated by the build-environment
   because Modules/ (which is added to sys.path for Setup-created modules)
   has 'zlib' and '_ctypes' directories without __init__.py's.

1 files changed, 17 insertions, 0 deletions

diff --git a/Lib/test/test_import.py b/Lib/test/test_import.py
index a72b8bd..effba3c 100644
--- a/Lib/test/test_import.py
+++ b/Lib/test/test_import.py
@@ -205,3 +205,20 @@ def test_import_name_binding():
     assert y is test.test_support, y.__name__
 
 test_import_name_binding()
+
+def test_import_initless_directory_warning():
+    import warnings
+    oldfilters = warnings.filters[:]
+    warnings.simplefilter('error', ImportWarning);
+    try:
+        # Just a random non-package directory we always expect to be
+        # somewhere in sys.path...
+        __import__("site-packages")
+    except ImportWarning:
+        pass
+    else:
+        raise AssertionError
+    finally:
+        warnings.filters = oldfilters
+
+test_import_initless_directory_warning()