Matter Sensor/Thermostat: Handle invalid unit conversions

drivers/SmartThings/matter-sensor/src/sub_drivers/air_quality_sensor/air_quality_sensor_handlers/attribute_handlers.lua

@@ -4,6 +4,7 @@
 local st_utils = require "st.utils"
 local capabilities = require "st.capabilities"
 local aqs_fields = require "sub_drivers.air_quality_sensor.air_quality_sensor_utils.fields"
+local aqs_utils = require "sub_drivers.air_quality_sensor.air_quality_sensor_utils.utils"
 
 local AirQualitySensorAttributeHandlers = {}
 
@@ -24,19 +25,16 @@ end
 
 function AirQualitySensorAttributeHandlers.measured_value_factory(capability_name, attribute, target_unit)
   return function(driver, device, ib, response)
-    if ib.data.value then
-      local reporting_unit = device:get_field(capability_name.."_unit") or aqs_fields.unit_default[capability_name]
-      local conversion_function = aqs_fields.conversion_tables[reporting_unit][target_unit]
-      if conversion_function then
-        local converted_value = conversion_function(ib.data.value)
-        device:emit_event_for_endpoint(ib.endpoint_id, attribute({value = converted_value, unit = aqs_fields.unit_strings[target_unit]}))
-        -- handle case where device profile supports both fineDustLevel and dustLevel
+    if not ib.data.value then return end
+    local reporting_unit = device:get_field(capability_name.."_unit") or aqs_fields.unit_default[capability_name]
+    local converted_value = aqs_utils.convert_value_to_unit(ib.data.value, reporting_unit, target_unit, capability_name)
+
+    if converted_value then
+      device:emit_event_for_endpoint(ib.endpoint_id, attribute({value = converted_value, unit = aqs_fields.unit_strings[target_unit]}))
+      -- handle case where device profile supports both fineDustLevel and dustLevel
         if capability_name == capabilities.fineDustSensor.NAME and device:supports_capability(capabilities.dustSensor) then
           device:emit_event_for_endpoint(ib.endpoint_id, capabilities.dustSensor.fineDustLevel({value = converted_value, unit = aqs_fields.unit_strings[target_unit]}))
         end
-      else
-        device.log.info_with({hub_logs=true}, string.format("Unsupported unit conversion from %s to %s", aqs_fields.unit_strings[reporting_unit], aqs_fields.unit_strings[target_unit]))
-      end
     end
   end
 end

drivers/SmartThings/matter-sensor/src/sub_drivers/air_quality_sensor/air_quality_sensor_utils/fields.lua

@@ -1,8 +1,9 @@
 -- Copyright © 2025 SmartThings, Inc.
 -- Licensed under the Apache License, Version 2.0
 
+local log = require "log"
 local version = require "version"
-local utils = require "st.utils"
+local st_utils = require "st.utils"
 local clusters = require "st.matter.clusters"
 local capabilities = require "st.capabilities"
 
@@ -149,30 +150,64 @@ AirQualitySensorFields.level_strings = {
   [clusters.CarbonMonoxideConcentrationMeasurement.types.LevelValueEnum.CRITICAL] = "hazardous",
 }
 
-AirQualitySensorFields.conversion_tables = {
+AirQualitySensorFields.MGM3_PPM_CONVERSION_FACTOR = 24.45
+
+-- measured in g/mol
+AirQualitySensorFields.molecular_weights = {
+  [capabilities.carbonDioxideMeasurement.NAME] = 44.010,
+  [capabilities.nitrogenDioxideMeasurement.NAME] = 28.014,
+  [capabilities.ozoneMeasurement.NAME] = 48.0,
+  [capabilities.formaldehydeMeasurement.NAME] = 30.031,
+  [capabilities.veryFineDustSensor.NAME] = "N/A",
+  [capabilities.fineDustSensor.NAME] = "N/A",
+  [capabilities.dustSensor.NAME] = "N/A",
+  [capabilities.radonMeasurement.NAME] = 222.018,
+  [capabilities.tvocMeasurement.NAME] = "N/A",
+}
+
+local function is_valid_molecular_weight(molecular_weight)
+  if type(molecular_weight) ~= "number" or molecular_weight <= 0 then
+    log.warn_with({hub_logs = true}, string.format("unit conversion molecular weight (%s) is not a valid number", molecular_weight))
+    return false
+  end
+  return true
+end
+
+AirQualitySensorFields.unit_conversion = {
   [units.PPM] = {
-    [units.PPM] = function(value) return utils.round(value) end,
-    [units.PPB] = function(value) return utils.round(value * (10^3)) end
-  },
+    [units.PPM] = function(value) return st_utils.round(value) end,
+    [units.PPB] = function(value) return st_utils.round(value * (10^3)) end,
+    [units.UGM3] = function(value, molecular_weight) if is_valid_molecular_weight(molecular_weight) then
+      return st_utils.round((value * molecular_weight * 10^3) / AirQualitySensorFields.MGM3_PPM_CONVERSION_FACTOR) end
+    end,
+    [units.MGM3] = function(value, molecular_weight) if is_valid_molecular_weight(molecular_weight) then
+      return st_utils.round((value * molecular_weight) / AirQualitySensorFields.MGM3_PPM_CONVERSION_FACTOR) end
+    end,},
   [units.PPB] = {
-    [units.PPM] = function(value) return utils.round(value/(10^3)) end,
-    [units.PPB] = function(value) return utils.round(value) end
+    [units.PPM] = function(value) return st_utils.round(value/(10^3)) end,
+    [units.PPB] = function(value) return st_utils.round(value) end,
   },
   [units.PPT] = {
-    [units.PPM] = function(value) return utils.round(value/(10^6)) end
+    [units.PPM] = function(value) return st_utils.round(value/(10^6)) end
   },
   [units.MGM3] = {
-    [units.UGM3] = function(value) return utils.round(value * (10^3)) end
+    [units.UGM3] = function(value) return st_utils.round(value * (10^3)) end,
+    [units.PPM] = function(value, molecular_weight) if is_valid_molecular_weight(molecular_weight) then
+      return st_utils.round((value * AirQualitySensorFields.MGM3_PPM_CONVERSION_FACTOR) / molecular_weight) end
+    end,
   },
   [units.UGM3] = {
-    [units.UGM3] = function(value) return utils.round(value) end
+    [units.UGM3] = function(value) return st_utils.round(value) end,
+    [units.PPM] = function(value, molecular_weight) if is_valid_molecular_weight(molecular_weight) then
+      return st_utils.round((value * AirQualitySensorFields.MGM3_PPM_CONVERSION_FACTOR) / (molecular_weight * 10^3)) end
+    end,
   },
   [units.NGM3] = {
-    [units.UGM3] = function(value) return utils.round(value/(10^3)) end
+    [units.UGM3] = function(value) return st_utils.round(value/(10^3)) end
   },
   [units.BQM3] = {
-    [units.PCIL] = function(value) return utils.round(value/37) end
-  }
+    [units.PCIL] = function(value) return st_utils.round(value/37) end
+  },
 }
 
 return AirQualitySensorFields

drivers/SmartThings/matter-sensor/src/sub_drivers/air_quality_sensor/air_quality_sensor_utils/utils.lua

@@ -1,6 +1,7 @@
 -- Copyright 2025 SmartThings, Inc.
 -- Licensed under the Apache License, Version 2.0
 
+local log = require "log"
 local capabilities = require "st.capabilities"
 local clusters = require "st.matter.clusters"
 local embedded_cluster_utils = require "sensor_utils.embedded_cluster_utils"
@@ -77,6 +78,18 @@ function AirQualitySensorUtils.set_supported_health_concern_values(device)
   end
 end
 
+function AirQualitySensorUtils.convert_value_to_unit(value, from_unit, to_unit, capability_name)
+  local conversion_function = fields.unit_conversion[from_unit] and fields.unit_conversion[from_unit][to_unit]
+  if not conversion_function then
+    log.info_with( {hub_logs = true} , string.format("Unsupported unit conversion from %s to %s", fields.unit_strings[from_unit], fields.unit_strings[to_unit]))
+    return
+  elseif type(value) ~= "number" then
+    log.info_with( {hub_logs = true} , string.format("unit conversion value (%s) is not a number", value))
+    return
+  end
+  return conversion_function(value, fields.molecular_weights[capability_name])
+end
+
 --- Deeply compare two values.
 --- Handles metatables. Can optionally ignore cycle checking and/or function differences.
 ---

drivers/SmartThings/matter-sensor/src/test/test_unsupported_unit_conversion.lua

@@ -0,0 +1,65 @@
+-- Copyright © 2025 SmartThings, Inc.
+-- Licensed under the Apache License, Version 2.0
+
+local test = require "integration_test"
+local capabilities = require "st.capabilities"
+
+-- Unit conversion utilities for sensor
+local air_quality_sensor_utils = require "sub_drivers.air_quality_sensor.air_quality_sensor_utils.utils"
+local air_quality_sensor_fields = require "sub_drivers.air_quality_sensor.air_quality_sensor_utils.fields"
+
+test.set_rpc_version(0)
+
+local units = air_quality_sensor_fields.units
+
+test.register_coroutine_test(
+  "Unsupported unit conversion from PPT to MGM3 should return nil",
+  function()
+    local result = air_quality_sensor_utils.convert_value_to_unit(100, units.PPT, units.MGM3, capabilities.ozoneMeasurement.NAME)
+    assert(result == nil, "Expected nil for unsupported PPT to MGM3 conversion, got: " .. tostring(result))
+  end
+)
+
+test.register_coroutine_test(
+  "Unsupported unit conversion from PPB to UGM3 should return nil",
+  function()
+    local result = air_quality_sensor_utils.convert_value_to_unit(100, units.PPB, units.UGM3, capabilities.carbonMonoxideMeasurement.NAME)
+    assert(result == nil, "Expected nil for unsupported PPB to UGM3 conversion, got: " .. tostring(result))
+  end
+)
+
+test.register_coroutine_test(
+  "Unsupported unit conversion from NGM3 to PPM should return nil",
+  function()
+    local result = air_quality_sensor_utils.convert_value_to_unit(100, units.NGM3, units.PPM, capabilities.carbonMonoxideMeasurement.NAME)
+    assert(result == nil, "Expected nil for unsupported NGM3 to PPM conversion, got: " .. tostring(result))
+  end
+)
+
+test.register_coroutine_test(
+  "Supported unit conversion from PPM to PPB should return correct value",
+  function()
+    local result = air_quality_sensor_utils.convert_value_to_unit(100, units.PPM, units.PPB, capabilities.carbonMonoxideMeasurement.NAME)
+    assert(result ~= nil, "Expected a value for supported PPM to PPB conversion")
+    assert(result == 100000, "Expected 100000 for PPM to PPB conversion, got: " .. tostring(result))
+  end
+)
+
+test.register_coroutine_test(
+  "Supported unit conversion from PPB to PPM should return correct value",
+  function()
+    local result = air_quality_sensor_utils.convert_value_to_unit(1000, units.PPB, units.PPM, capabilities.carbonMonoxideMeasurement.NAME)
+    assert(result ~= nil, "Expected a value for supported PPB to PPM conversion")
+    assert(result == 1, "Expected 1 for PPB to PPM conversion, got: " .. tostring(result))
+  end
+)
+
+test.register_coroutine_test(
+  "Unit conversion with non-numeric value should return nil",
+  function()
+    local result = air_quality_sensor_utils.convert_value_to_unit("not a number", units.PPM, units.PPB, capabilities.carbonMonoxideMeasurement.NAME)
+    assert(result == nil, "Expected nil when value is not a number, got: " .. tostring(result))
+  end
+)
+
+test.run_registered_tests()

drivers/SmartThings/matter-thermostat/src/test/test_unsupported_unit_conversion.lua

@@ -0,0 +1,65 @@
+-- Copyright © 2025 SmartThings, Inc.
+-- Licensed under the Apache License, Version 2.0
+
+local test = require "integration_test"
+local capabilities = require "st.capabilities"
+
+-- Unit conversion utilities for thermostat
+local thermostat_utils = require "thermostat_utils.utils"
+local thermostat_fields = require "thermostat_utils.fields"
+
+test.set_rpc_version(0)
+
+local units = thermostat_fields.units
+
+test.register_coroutine_test(
+  "Unsupported unit conversion from PPT to MGM3 should return nil",
+  function()
+    local result = thermostat_utils.convert_value_to_unit(100, units.PPT, units.MGM3, capabilities.ozoneMeasurement.NAME)
+    assert(result == nil, "Expected nil for unsupported PPT to MGM3 conversion, got: " .. tostring(result))
+  end
+)
+
+test.register_coroutine_test(
+  "Unsupported unit conversion from PPB to UGM3 should return nil",
+  function()
+    local result = thermostat_utils.convert_value_to_unit(100, units.PPB, units.UGM3, capabilities.carbonMonoxideMeasurement.NAME)
+    assert(result == nil, "Expected nil for unsupported PPB to UGM3 conversion, got: " .. tostring(result))
+  end
+)
+
+test.register_coroutine_test(
+  "Unsupported unit conversion from NGM3 to PPM should return nil",
+  function()
+    local result = thermostat_utils.convert_value_to_unit(100, units.NGM3, units.PPM, capabilities.carbonMonoxideMeasurement.NAME)
+    assert(result == nil, "Expected nil for unsupported NGM3 to PPM conversion, got: " .. tostring(result))
+  end
+)
+
+test.register_coroutine_test(
+  "Supported unit conversion from PPM to PPB should return correct value",
+  function()
+    local result = thermostat_utils.convert_value_to_unit(100, units.PPM, units.PPB, capabilities.carbonMonoxideMeasurement.NAME)
+    assert(result ~= nil, "Expected a value for supported PPM to PPB conversion")
+    assert(result == 100000, "Expected 100000 for PPM to PPB conversion, got: " .. tostring(result))
+  end
+)
+
+test.register_coroutine_test(
+  "Supported unit conversion from PPB to PPM should return correct value",
+  function()
+    local result = thermostat_utils.convert_value_to_unit(1000, units.PPB, units.PPM, capabilities.carbonMonoxideMeasurement.NAME)
+    assert(result ~= nil, "Expected a value for supported PPB to PPM conversion")
+    assert(result == 1, "Expected 1 for PPB to PPM conversion, got: " .. tostring(result))
+  end
+)
+
+test.register_coroutine_test(
+  "Unit conversion with non-numeric value should return nil",
+  function()
+    local result = thermostat_utils.convert_value_to_unit("not a number", units.PPM, units.PPB, capabilities.carbonMonoxideMeasurement.NAME)
+    assert(result == nil, "Expected nil when value is not a number, got: " .. tostring(result))
+  end
+)
+
+test.run_registered_tests()

drivers/SmartThings/matter-thermostat/src/thermostat_handlers/attribute_handlers.lua

@@ -494,23 +494,15 @@ end
 
 function AttributeHandlers.concentration_measured_value_factory(capability_name, attribute, target_unit)
   return function(driver, device, ib, response)
-    local reporting_unit = device:get_field(capability_name.."_unit")
+    if not ib.data.value then return end
+    local reporting_unit = device:get_field(capability_name.."_unit") or fields.unit_default[capability_name]
+    local converted_value = thermostat_utils.convert_value_to_unit(ib.data.value, reporting_unit, target_unit, capability_name)
 
-    if not reporting_unit then
-      reporting_unit = fields.unit_default[capability_name]
-      device:set_field(capability_name.."_unit", reporting_unit, {persist = true})
-    end
-
-    local value = nil
-    if reporting_unit then
-      value = thermostat_utils.unit_conversion(ib.data.value, reporting_unit, target_unit, capability_name)
-    end
-
-    if value then
-      device:emit_event_for_endpoint(ib.endpoint_id, attribute({value = value, unit = fields.unit_strings[target_unit]}))
+    if converted_value then
+      device:emit_event_for_endpoint(ib.endpoint_id, attribute({value = converted_value, unit = fields.unit_strings[target_unit]}))
       -- handle case where device profile supports both fineDustLevel and dustLevel
       if capability_name == capabilities.fineDustSensor.NAME and device:supports_capability(capabilities.dustSensor) then
-        device:emit_event_for_endpoint(ib.endpoint_id, capabilities.dustSensor.fineDustLevel({value = value, unit = fields.unit_strings[target_unit]}))
+        device:emit_event_for_endpoint(ib.endpoint_id, capabilities.dustSensor.fineDustLevel({value = converted_value, unit = fields.unit_strings[target_unit]}))
       end
     end
   end

drivers/SmartThings/matter-thermostat/src/thermostat_utils/fields.lua

@@ -1,6 +1,7 @@
 -- Copyright © 2025 SmartThings, Inc.
 -- Licensed under the Apache License, Version 2.0
 
+local log = require "log"
 local version = require "version"
 local capabilities = require "st.capabilities"
 local clusters = require "st.matter.clusters"
@@ -205,13 +206,24 @@ ThermostatFields.molecular_weights = {
   [capabilities.tvocMeasurement.NAME] = "N/A",
 }
 
-ThermostatFields.conversion_tables = {
+local function is_valid_molecular_weight(molecular_weight)
+  if type(molecular_weight) ~= "number" or molecular_weight <= 0 then
+    log.warn_with({hub_logs = true}, string.format("unit conversion molecular weight (%s) is not a valid number", molecular_weight))
+    return false
+  end
+  return true
+end
+
+ThermostatFields.unit_conversion = {
   [units.PPM] = {
     [units.PPM] = function(value) return st_utils.round(value) end,
     [units.PPB] = function(value) return st_utils.round(value * (10^3)) end,
-    [units.UGM3] = function(value, molecular_weight) return st_utils.round((value * molecular_weight * 10^3) / ThermostatFields.MGM3_PPM_CONVERSION_FACTOR) end,
-    [units.MGM3] = function(value, molecular_weight) return st_utils.round((value * molecular_weight) / ThermostatFields.MGM3_PPM_CONVERSION_FACTOR) end,
-  },
+    [units.UGM3] = function(value, molecular_weight) if is_valid_molecular_weight(molecular_weight) then
+      return st_utils.round((value * molecular_weight * 10^3) / ThermostatFields.MGM3_PPM_CONVERSION_FACTOR) end
+    end,
+    [units.MGM3] = function(value, molecular_weight) if is_valid_molecular_weight(molecular_weight) then
+      return st_utils.round((value * molecular_weight) / ThermostatFields.MGM3_PPM_CONVERSION_FACTOR) end
+    end,},
   [units.PPB] = {
     [units.PPM] = function(value) return st_utils.round(value/(10^3)) end,
     [units.PPB] = function(value) return st_utils.round(value) end,
@@ -221,11 +233,15 @@ ThermostatFields.conversion_tables = {
   },
   [units.MGM3] = {
     [units.UGM3] = function(value) return st_utils.round(value * (10^3)) end,
-    [units.PPM] = function(value, molecular_weight) return st_utils.round((value * ThermostatFields.MGM3_PPM_CONVERSION_FACTOR) / molecular_weight) end,
+    [units.PPM] = function(value, molecular_weight) if is_valid_molecular_weight(molecular_weight) then
+      return st_utils.round((value * ThermostatFields.MGM3_PPM_CONVERSION_FACTOR) / molecular_weight) end
+    end,
   },
   [units.UGM3] = {
     [units.UGM3] = function(value) return st_utils.round(value) end,
-    [units.PPM] = function(value, molecular_weight) return st_utils.round((value * ThermostatFields.MGM3_PPM_CONVERSION_FACTOR) / (molecular_weight * 10^3)) end,
+    [units.PPM] = function(value, molecular_weight) if is_valid_molecular_weight(molecular_weight) then
+      return st_utils.round((value * ThermostatFields.MGM3_PPM_CONVERSION_FACTOR) / (molecular_weight * 10^3)) end
+    end,
   },
   [units.NGM3] = {
     [units.UGM3] = function(value) return st_utils.round(value/(10^3)) end

drivers/SmartThings/matter-thermostat/src/thermostat_utils/utils.lua

@@ -180,18 +180,15 @@ function ThermostatUtils.get_device_type(device)
   return main_device_type
 end
 
-function ThermostatUtils.unit_conversion(value, from_unit, to_unit, capability_name)
-  local conversion_function = fields.conversion_tables[from_unit] and fields.conversion_tables[from_unit][to_unit] or nil
+function ThermostatUtils.convert_value_to_unit(value, from_unit, to_unit, capability_name)
+  local conversion_function = fields.unit_conversion[from_unit] and fields.unit_conversion[from_unit][to_unit]
   if not conversion_function then
     log.info_with( {hub_logs = true} , string.format("Unsupported unit conversion from %s to %s", fields.unit_strings[from_unit], fields.unit_strings[to_unit]))
     return
-  end
-
-  if not value then
-    log.info_with( {hub_logs = true} , "unit conversion value is nil")
+  elseif type(value) ~= "number" then
+    log.info_with( {hub_logs = true} , string.format("unit conversion value (%s) is not a number", value))
     return
   end
-
   return conversion_function(value, fields.molecular_weights[capability_name])
 end