regrtest: add -k and -K options to filter tests by function/file names

Lib/test/support.py

 """Supporting definitions for the Python regression tests."""
 
 if __name__ != 'test.support':
     raise ImportError('support must be imported from the test package')
 
 import contextlib
 import errno
 import functools
 import gc
 import socket
@@ skipping 1252 matching lines @@
         elif len(result.failures) == 1 and not result.errors:
             err = result.failures[0][1]
         else:
             err = "multiple errors occurred"
             if not verbose: err += "; run in verbose mode for details"
         raise TestFailed(err)
 
 
 def run_unittest(*classes):
     """Run tests from unittest.TestCase-derived classes."""
+    regexes = run_unittest.regexes
+    if regexes:
+        def filter_test(name):
+            return any(regex.search(name) for regex in regexes)
+    else:
+        filter_test = None
     valid_types = (unittest.TestSuite, unittest.TestCase)
     suite = unittest.TestSuite()
     for cls in classes:
         if isinstance(cls, str):
             if cls in sys.modules:
-                suite.addTest(unittest.findTestCases(sys.modules[cls]))
+                suite.addTest(unittest.findTestCases(sys.modules[cls], filter=filter_test))
             else:
                 raise ValueError("str arguments must be keys in sys.modules")
         elif isinstance(cls, valid_types):
             suite.addTest(cls)
         else:
-            suite.addTest(unittest.makeSuite(cls))
+            suite.addTest(unittest.makeSuite(cls, filter=filter_test))
     _run_suite(suite)
+# List of regex objects used to filter the tests by their function name.
+# An empty list means that all tests are used.
+run_unittest.regexes = []
 
 
 #=======================================================================
 # doctest driver.
 
 def run_doctest(module, verbosity=None):
     """Run doctest on the given module.  Return (#failures, #tests).
 
     If optional argument verbosity is not specified (or is None), pass
     support's belief about verbosity on to doctest.  Else doctest's
@@ skipping 301 matching lines @@
     def cleanup():
         if attr_is_local:
             setattr(object_to_patch, attr_name, old_value)
         else:
             delattr(object_to_patch, attr_name)
 
     test_instance.addCleanup(cleanup)
 
     # actually override the attribute
     setattr(object_to_patch, attr_name, new_value)