Allow forming a network quickly, without writing keys and tables (#208)

* Allow forming a network quickly, without writing keys and tables

* Add a unit test

tests/api/test_network_state.py

@@ -1,4 +1,5 @@
 import logging
+from unittest import mock
 
 import pytest
 
@@ -10,6 +11,7 @@
     FORMED_DEVICES,
     BaseZStack1CC2531,
     FormedZStack3CC2531,
+    FormedLaunchpadCC26X2R1,
 )
 
 
@@ -92,3 +94,23 @@ async def test_state_write_tclk_zstack3(device, make_connected_znp, caplog):
 
     # TCLK was not changed
     assert formed_znp.network_info == empty_znp.network_info
+
+
+@pytest.mark.parametrize("device", ALL_DEVICES)
+async def test_write_settings_fast(device, make_connected_znp):
+    formed_znp, _ = await make_connected_znp(server_cls=FormedLaunchpadCC26X2R1)
+    await formed_znp.load_network_info()
+    formed_znp.close()
+
+    znp, _ = await make_connected_znp(server_cls=device)
+
+    formed_znp.network_info.stack_specific["form_quickly"] = True
+
+    with mock.patch("zigpy_znp.znp.security.write_devices") as mock_write_devices:
+        await znp.write_network_info(
+            network_info=formed_znp.network_info,
+            node_info=formed_znp.node_info,
+        )
+
+    # We don't waste time writing device info
+    assert len(mock_write_devices.mock_awaits) == 0

zigpy_znp/api.py

@@ -344,7 +344,8 @@ async def write_network_info(
         """
         from zigpy_znp.znp import security
 
-        await self.reset_network_info()
+        if not network_info.stack_specific.get("form_quickly", False):
+            await self.reset_network_info()
 
         # Form a network with completely random settings to get NVRAM to a known state
         for item, value in {
@@ -377,6 +378,14 @@ async def write_network_info(
         await self.start_network()
         await self.reset()
 
+        if network_info.stack_specific.get("form_quickly", False):
+            await self.nvram.osal_write(
+                OsalNvIds.ZIGPY_ZNP_MIGRATION_ID,
+                t.uint8_t(NVRAM_MIGRATION_ID),
+                create=True,
+            )
+            return
+
         LOGGER.debug("Writing actual network settings")
 
         # Now that we have a formed network, update its state