Let expect_tests stop walking across certain packages.

expect_tests/main.py

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import argparse
 import multiprocessing
 import pkgutil
 import sys
 
 from expect_tests import handle_list, handle_debug, handle_train, handle_test
@@ skipping 116 matching lines @@
   del opts.test_list
   del opts.mode
 
   return opts
 
 
 def find_all_modules():
   sys.path.insert(0, '.')
 
   ret = []
+  blacklist = set()
   for importer, modname, ispkg in pkgutil.walk_packages(path=['.']):
-    if not ispkg and modname.endswith('_test'):
+    if ispkg and getattr(importer.find_module(modname).load_module(modname),
+                         '_expect_tests_stop_walk', False):
+        blacklist.add(modname)
+      continue
+    if modname.endswith('_test'):
+      if any(modname.startswith(pkg) for pkg in blacklist):
+        continue
       if modname in sys.modules:
         ret.append(sys.modules[modname])
       else:
         ret.append(importer.find_module(modname).load_module(modname))
 
   return ret
 
 
 def get_test_gens(test_modules):
   if test_modules is ALL_MODULES:
@@ skipping 53 matching lines @@
     cover_ctx.cleanup()
     if (not killed and
         not skip_loop and (
           opts.force_coverage or not opts.test_glob)):
       if not cover_ctx.report(opts.verbose):
         sys.exit(2)
 
     sys.exit(error or killed)
   except KeyboardInterrupt:
     pass