Fix warnings during final GC of the test suite in python 3.4a1.

3.4 can GC things that were uncollectable before, like abandoned generators.
It also seems generates ResourceWarnings for unclosed files in places
where older versions did not.

tornado/test/httpclient_test.py

@@ -442,16 +442,19 @@ def setUp(self):
 
         sock, self.port = bind_unused_port()
         app = Application([('/', HelloWorldHandler)])
-        server = HTTPServer(app, io_loop=self.server_ioloop)
-        server.add_socket(sock)
+        self.server = HTTPServer(app, io_loop=self.server_ioloop)
+        self.server.add_socket(sock)
 
         self.server_thread = threading.Thread(target=self.server_ioloop.start)
         self.server_thread.start()
 
         self.http_client = HTTPClient()
 
     def tearDown(self):
-        self.server_ioloop.add_callback(self.server_ioloop.stop)
+        def stop_server():
+            self.server.stop()
+            self.server_ioloop.stop()
+        self.server_ioloop.add_callback(stop_server)
         self.server_thread.join()
         self.http_client.close()
         self.server_ioloop.close(all_fds=True)

tornado/test/simple_httpclient_test.py

@@ -122,9 +122,9 @@ def test_singleton(self):
                         SimpleAsyncHTTPClient(self.io_loop,
                                               force_instance=True))
         # different IOLoops use different objects
-        io_loop2 = IOLoop()
-        self.assertTrue(SimpleAsyncHTTPClient(self.io_loop) is not
-                        SimpleAsyncHTTPClient(io_loop2))
+        with closing(IOLoop()) as io_loop2:
+            self.assertTrue(SimpleAsyncHTTPClient(self.io_loop) is not
+                            SimpleAsyncHTTPClient(io_loop2))
 
     def test_connection_limit(self):
         with closing(self.create_client(max_clients=2)) as client:

tornado/test/stack_context_test.py

@@ -219,12 +219,21 @@ def f3():
     def test_yield_in_with(self):
         @gen.engine
         def f():
-            with StackContext(functools.partial(self.context, 'c1')):
-                # This yield is a problem: the generator will be suspended
-                # and the StackContext's __exit__ is not called yet, so
-                # the context will be left on _state.contexts for anything
-                # that runs before the yield resolves.
-                yield gen.Task(self.io_loop.add_callback)
+            try:
+                with StackContext(functools.partial(self.context, 'c1')):
+                    # This yield is a problem: the generator will be suspended
+                    # and the StackContext's __exit__ is not called yet, so
+                    # the context will be left on _state.contexts for anything
+                    # that runs before the yield resolves.
+                    yield gen.Task(self.io_loop.add_callback)
+            except StackContextInconsistentError:
+                # In python <= 3.3, this suspended generator is never garbage
+                # collected, so it remains suspended in the 'yield' forever.
+                # Starting in 3.4, it is made collectable by raising
+                # a GeneratorExit exception from the yield, which gets
+                # converted into a StackContextInconsistentError by the
+                # exit of the 'with' block.
+                pass
 
         with self.assertRaises(StackContextInconsistentError):
             f()
@@ -242,8 +251,11 @@ def test_yield_in_with_exception_stack_context(self):
         # As above, but with ExceptionStackContext instead of StackContext.
         @gen.engine
         def f():
-            with ExceptionStackContext(lambda t, v, tb: False):
-                yield gen.Task(self.io_loop.add_callback)
+            try:
+                with ExceptionStackContext(lambda t, v, tb: False):
+                    yield gen.Task(self.io_loop.add_callback)
+            except StackContextInconsistentError:
+                pass
 
         with self.assertRaises(StackContextInconsistentError):
             f()