Fix command line tools not handling stdin/stdout pipes properly

tests/tools/test_network_backup_restore.py

@@ -21,6 +21,7 @@
     CoroutineMock,
     BaseZStack1CC2531,
     BaseZStack3CC2531,
+    FormedZStack1CC2531,
     BaseLaunchpadCC26X2R1,
 )
 from ..application.test_startup import DEV_NETWORK_SETTINGS
@@ -118,6 +119,17 @@ async def test_network_backup_empty(device, make_znp_server):
         await network_backup([znp_server._port_path, "-o", "-"])
 
 
+@pytest.mark.parametrize("device", [FormedZStack1CC2531])
+@pytest.mark.asyncio
+async def test_network_backup_pipe(device, make_znp_server, capsys):
+    znp_server = make_znp_server(server_cls=device)
+
+    await network_backup([znp_server._port_path, "-o", "-"])
+    stdout, stderr = capsys.readouterr()
+
+    validate_backup_json(json.loads(stdout))
+
+
 @pytest.mark.parametrize("device", FORMED_DEVICES)
 @pytest.mark.asyncio
 async def test_network_backup_formed(device, make_znp_server, tmp_path):

zigpy_znp/tools/common.py

@@ -155,7 +155,7 @@ def close(self):
         return
 
     def __enter__(self):
-        return
+        return self
 
     def __exit__(self, exc_type, exc_value, traceback):
         return