Add a test wait.

Author: Lukasa

test/test_integration.py

@@ -480,7 +480,7 @@ def socket_handler(listener):
             d.flags.add('END_STREAM')
             sock.send(d.serialize())
 
-            send_event.set()
+            send_event.wait()
             sock.close()
 
         self._start_server(socket_handler)
@@ -494,6 +494,8 @@ def socket_handler(listener):
         assert r.headers[b'Content-Type'] == b'not/real'
         assert r.content == b'1234567890' * 2
 
+        send_event.set()
+
         self.tear_down()
 
     def test_adapter_sending_values(self, monkeypatch):