Check for stray threads from tests and fail if found

testing_support/auto_stub.py

Index: testing_support/auto_stub.py
diff --git a/testing_support/auto_stub.py b/testing_support/auto_stub.py
index e1155a64ae71f4ec5e0607ad95dd2eb352dd14c8..bcede8773a416835d1d8b5373201ac302af3a82e 100644
--- a/testing_support/auto_stub.py
+++ b/testing_support/auto_stub.py
@@ -4,7 +4,8 @@
 
 import collections
 import inspect
-import unittest
+
+from testing_support import thread_watcher
 
 
 class AutoStubMixIn(object):
@@ -63,8 +64,8 @@ class SimpleMock(object):
         caller_name, ', '.join(filter(None, [str_args, str_kwargs]))))
 
 
-class TestCase(unittest.TestCase, AutoStubMixIn):
+class TestCase(thread_watcher.TestCase, AutoStubMixIn):

[tandrii(chromium), 2016/06/13 17:03:27]

i'd not touch this one. Provide your testcase, yes, but don't make it default.
Instead, switch to it to default on a case by case basis.

[Sergiy Byelozyorov, 2016/06/14 06:12:14]

Developers are used to inherit from auto_stub.TestCase or trial_dir.TestCase.
Given this, all new tests that are added will not have thread_watcher built-in.
I'd rather have all new tests written to leak no threads.

[tandrii(chromium), 2016/06/14 10:21:43]

it's a trade off for how easy it'd be to roll this into infra. But I think
long-term, I'm 100% with you. Thus, if you keep this as it is, then you should
make sure all tests are fixed (which is good in itself, but may take time).

[Sergiy Byelozyorov, 2016/06/14 19:47:01]

Acknowledged.

   """Adds self.mock() and self.has_failed() to a TestCase."""
   def tearDown(self):
     AutoStubMixIn.tearDown(self)
-    unittest.TestCase.tearDown(self)
+    super(TestCase, self).tearDown()

[tandrii(chromium), 2016/06/13 17:03:27]

this is bad. It should be explicit as it used to be before.

[Sergiy Byelozyorov, 2016/06/14 06:12:14]

We do it differently everywhere else. Why should it be explicit? In fact, if
it's explicit we then have to update this call site each time we choose to
change the base class.

[tandrii(chromium), 2016/06/14 10:21:43]

Oh, yes, I suppose it's Ok. I prefer explicit because I don't understand the
order of resolution in super() when class inherits from several classes.

[Sergiy Byelozyorov, 2016/06/14 19:47:01]

Acknowledged.