Implement channel migration (#139)

tests/test_application.py

@@ -587,3 +587,11 @@ async def mock_at_command(cmd, *args):
     await app.reset_network_info()
 
     app._api._at_command.assert_called_once_with("NR", 0)
+
+
+async def test_move_network_to_channel(app):
+    app._api._queued_at = mock.AsyncMock(spec=XBee._at_command)
+    await app._move_network_to_channel(26, new_nwk_update_id=1)
+
+    assert len(app._api._queued_at.mock_calls) == 1
+    app._api._queued_at.assert_any_call("SC", 1 << (26 - 11))

zigpy_xbee/zigbee/application.py

@@ -161,6 +161,13 @@ async def write_network_info(self, *, network_info, node_info):
         )
         LOGGER.debug("Association state: %s", association_state)
 
+    async def _move_network_to_channel(
+        self, new_channel: int, new_nwk_update_id: int
+    ) -> None:
+        """Moves the coordinator to a new channel."""
+        scan_bitmask = 1 << (new_channel - 11)
+        await self._api._queued_at("SC", scan_bitmask)
+
     async def force_remove(self, dev):
         """Forcibly remove device from NCP."""
         pass