Enable warnings when running our tests. Rename (the undocumented)...

Enable warnings when running our tests. Rename (the undocumented) threadpool.ThreadResult.async to async_watcher because it's a keyword in 3.7, as exposed by warnings.

src/gevent/threadpool.py

@@ -267,7 +267,7 @@ class ThreadPool(GroupMappingMixin):
 class ThreadResult(object):
 
     # Using slots here helps to debug reference cycles/leaks
-    __slots__ = ('exc_info', 'async', '_call_when_ready', 'value',
+    __slots__ = ('exc_info', 'async_watcher', '_call_when_ready', 'value',
                  'context', 'hub', 'receiver')
 
     def __init__(self, receiver, hub=None, call_when_ready=None):
@@ -278,16 +278,16 @@ class ThreadResult(object):
         self.context = None
         self.value = None
         self.exc_info = ()
-        self.async = hub.loop.async()
+        self.async_watcher = hub.loop.async()
         self._call_when_ready = call_when_ready
-        self.async.start(self._on_async)
+        self.async_watcher.start(self._on_async)
 
     @property
     def exception(self):
         return self.exc_info[1] if self.exc_info else None
 
     def _on_async(self):
-        self.async.stop()
+        self.async_watcher.stop()
         if self._call_when_ready:
             # Typically this is pool.semaphore.release and we have to
             # call this in the Hub; if we don't we get the dreaded
@@ -297,7 +297,7 @@ class ThreadResult(object):
             if self.exc_info:
                 self.hub.handle_error(self.context, *self.exc_info)
             self.context = None
-            self.async = None
+            self.async_watcher = None
             self.hub = None
             self._call_when_ready = None
             if self.receiver is not None:
@@ -309,17 +309,17 @@ class ThreadResult(object):
                 self.exc_info = (self.exc_info[0], self.exc_info[1], None)
 
     def destroy(self):
-        if self.async is not None:
-            self.async.stop()
-        self.async = None
+        if self.async_watcher is not None:
+            self.async_watcher.stop()
+        self.async_watcher = None
         self.context = None
         self.hub = None
         self._call_when_ready = None
         self.receiver = None
 
     def _ready(self):
-        if self.async is not None:
-            self.async.send()
+        if self.async_watcher is not None:
+            self.async_watcher.send()
 
     def set(self, value):
         self.value = value

src/greentest/greentest.py

@@ -413,6 +413,21 @@ class TestCase(TestCaseMetaClass("NewBase", (BaseTestCase,), {})):
             del self.close_on_teardown
         except AttributeError:
             pass
+        super(TestCase, self).tearDown()
+
+    @classmethod
+    def setUpClass(cls):
+        import warnings
+        cls._warning_cm = warnings.catch_warnings()
+        cls._warning_cm.__enter__()
+        if not sys.warnoptions:
+            warnings.simplefilter('default')
+        super(TestCase, cls).setUpClass()
+
+    @classmethod
+    def tearDownClass(cls):
+        cls._warning_cm.__exit__(None, None, None)
+        super(TestCase, cls).tearDownClass()
 
     def _close_on_teardown(self, resource):
         if 'close_on_teardown' not in self.__dict__: