add asynccontextmanager utility for a pair of connected hosts

tests/factories.py

@@ -1,4 +1,5 @@
 import asyncio
+from contextlib import asynccontextmanager
 from typing import Dict, Tuple
 
 import factory
@@ -163,6 +164,14 @@ async def host_pair_factory(is_secure) -> Tuple[BasicHost, BasicHost]:
     return hosts[0], hosts[1]
 
 
+@asynccontextmanager
+async def pair_of_connected_hosts(is_secure=True):
+    a, b = await host_pair_factory(is_secure)
+    yield a, b
+    close_tasks = (a.close(), b.close())
+    await asyncio.gather(*close_tasks)
+
+
 async def swarm_conn_pair_factory(
     is_secure: bool, muxer_opt: TMuxerOptions = None
 ) -> Tuple[SwarmConn, Swarm, SwarmConn, Swarm]: