Perform initial update only using the sysinfo query (#199)

Some devices are known to fail when trying to query non-supported modules like emeter information.
This commit makes the initial update() only request the sysinfo, followed up by a second query
if emeter is supported by the device.

kasa/smartdevice.py

@@ -291,18 +291,33 @@ class SmartDevice:
         return await self._query_helper("system", "get_sysinfo")
 
     async def update(self):
-        """Update some of the attributes.
+        """Query the device to update the data.
 
-        Needed for methods that are decorated with `requires_update`.
+        Needed for properties that are decorated with `requires_update`.
         """
         req = {}
         req.update(self._create_request("system", "get_sysinfo"))
 
-        # Check for emeter if we were never updated, or if the device has emeter
+        # If this is the initial update, check only for the sysinfo
-        if self._last_update is None or self.has_emeter:
+        # This is necessary as some devices crash on unexpected modules
-            req.update(self._create_emeter_request())
+        # See #105, #120, #161
+        if self._last_update is None:
+            _LOGGER.debug("Performing the initial update to obtain sysinfo")
+            self._last_update = await self.protocol.query(self.host, req)
+            self._sys_info = self._last_update["system"]["get_sysinfo"]
+            # If the device has no emeter, we are done for the initial update
+            # Otherwise we will follow the regular code path to also query
+            # the emeter data also during the initial update
+            if not self.has_emeter:
+                return
+
+        if self.has_emeter:
+            _LOGGER.debug(
+                "The device has emeter, querying its information along sysinfo"
+            )
+            req.update(self._create_emeter_request())
+
         self._last_update = await self.protocol.query(self.host, req)
-        # TODO: keep accessible for tests
         self._sys_info = self._last_update["system"]["get_sysinfo"]
 
     def update_from_discover_info(self, info):

kasa/tests/conftest.py

@@ -35,7 +35,7 @@ STRIPS = {"HS107", "HS300", "KP303", "KP400"}
 DIMMERS = {"HS220"}
 
 DIMMABLE = {*BULBS, *DIMMERS}
-WITH_EMETER = {"HS110", "HS300", *BULBS, *STRIPS}
+WITH_EMETER = {"HS110", "HS300", *BULBS}
 
 ALL_DEVICES = BULBS.union(PLUGS).union(STRIPS).union(DIMMERS)
 

kasa/tests/test_smartdevice.py

@@ -5,7 +5,7 @@ import pytest  # type: ignore # https://github.com/pytest-dev/pytest/issues/3342
 
 from kasa import SmartDeviceException
 
-from .conftest import handle_turn_on, pytestmark, turn_on
+from .conftest import handle_turn_on, has_emeter, no_emeter, pytestmark, turn_on
 from .newfakes import PLUG_SCHEMA, TZ_SCHEMA, FakeTransportProtocol
 
 
@@ -17,7 +17,24 @@ async def test_invalid_connection(dev):
     with patch.object(FakeTransportProtocol, "query", side_effect=SmartDeviceException):
         with pytest.raises(SmartDeviceException):
             await dev.update()
-            dev.is_on
+
+
+@has_emeter
+async def test_initial_update_emeter(dev, mocker):
+    """Test that the initial update performs second query if emeter is available."""
+    dev._last_update = None
+    spy = mocker.spy(dev.protocol, "query")
+    await dev.update()
+    assert spy.call_count == 2
+
+
+@no_emeter
+async def test_initial_update_no_emeter(dev, mocker):
+    """Test that the initial update performs second query if emeter is available."""
+    dev._last_update = None
+    spy = mocker.spy(dev.protocol, "query")
+    await dev.update()
+    assert spy.call_count == 1
 
 
 async def test_query_helper(dev):