Issue #4384: Added logging integration with warnings module using captureWarnings(). This change includes a NullHandler which does nothing; it will be of use to library developers who want to avoid the "No handlers could be found for logger XXX" message which can appear if the library user doesn't configure logging.

Lib/test/test_logging.py

@@ -18,7 +18,7 @@
 
 """Test harness for the logging module. Run all tests.
 
-Copyright (C) 2001-2002 Vinay Sajip. All Rights Reserved.
+Copyright (C) 2001-2008 Vinay Sajip. All Rights Reserved.
 """
 
 import logging
@@ -44,6 +44,7 @@
 import time
 import types
 import unittest
+import warnings
 import weakref
 
 
@@ -885,6 +886,32 @@ def test_encoding_plain_file(self):
             if os.path.isfile(fn):
                 os.remove(fn)
 
+class WarningsTest(BaseTest):
+    def test_warnings(self):
+        logging.captureWarnings(True)
+        warnings.filterwarnings("always", category=UserWarning)
+        try:
+            file = cStringIO.StringIO()
+            h = logging.StreamHandler(file)
+            logger = logging.getLogger("py.warnings")
+            logger.addHandler(h)
+            warnings.warn("I'm warning you...")
+            logger.removeHandler(h)
+            s = file.getvalue()
+            h.close()
+            self.assertTrue(s.find("UserWarning: I'm warning you...\n") > 0)
+
+            #See if an explicit file uses the original implementation
+            file = cStringIO.StringIO()
+            warnings.showwarning("Explicit", UserWarning, "dummy.py", 42, file,
+                                 "Dummy line")
+            s = file.getvalue()
+            file.close()
+            self.assertEqual(s, "dummy.py:42: UserWarning: Explicit\n  Dummy line\n")
+        finally:
+            warnings.resetwarnings()
+            logging.captureWarnings(False)
+
 # Set the locale to the platform-dependent default.  I have no idea
 # why the test does this, but in any case we save the current locale
 # first and restore it at the end.
@@ -893,7 +920,7 @@ def test_main():
     run_unittest(BuiltinLevelsTest, BasicFilterTest,
                     CustomLevelsAndFiltersTest, MemoryHandlerTest,
                     ConfigFileTest, SocketHandlerTest, MemoryTest,
-                    EncodingTest)
+                    EncodingTest, WarningsTest)
 
 if __name__ == "__main__":
     test_main()