Refactor sensor configuration handling in tests and implementation

- Add skipCollection propery
- Ensure that sensors are initialized as an empty map

beszel/internal/agent/sensors.go

@@ -18,21 +18,26 @@ type SensorConfig struct {
 	primarySensor  string
 	isBlacklist    bool
 	hasWildcards   bool
+	skipCollection bool
 }
 
 func (a *Agent) newSensorConfig() *SensorConfig {
 	primarySensor, _ := GetEnv("PRIMARY_SENSOR")
 	sysSensors, _ := GetEnv("SYS_SENSORS")
-	sensors, _ := GetEnv("SENSORS")
+	sensorsEnvVal, sensorsSet := GetEnv("SENSORS")
+	skipCollection := sensorsSet && sensorsEnvVal == ""
 
-	return a.newSensorConfigWithEnv(primarySensor, sysSensors, sensors)
+	return a.newSensorConfigWithEnv(primarySensor, sysSensors, sensorsEnvVal, skipCollection)
 }
 
 // newSensorConfigWithEnv creates a SensorConfig with the provided environment variables
-func (a *Agent) newSensorConfigWithEnv(primarySensor, sysSensors, sensors string) *SensorConfig {
+// sensorsSet indicates if the SENSORS environment variable was explicitly set (even to empty string)
+func (a *Agent) newSensorConfigWithEnv(primarySensor, sysSensors, sensorsEnvVal string, skipCollection bool) *SensorConfig {
 	config := &SensorConfig{
 		context:        context.Background(),
 		primarySensor:  primarySensor,
+		skipCollection: skipCollection,
+		sensors:        make(map[string]struct{}),
 	}
 
 	// Set sensors context (allows overriding sys location for sensors)
@@ -43,16 +48,13 @@ func (a *Agent) newSensorConfigWithEnv(primarySensor, sysSensors, sensors string
 		)
 	}
 
-	// Set sensors whitelist
-	if sensors != "" {
 	// handle blacklist
-		if strings.HasPrefix(sensors, "-") {
+	if strings.HasPrefix(sensorsEnvVal, "-") {
 		config.isBlacklist = true
-			sensors = sensors[1:]
+		sensorsEnvVal = sensorsEnvVal[1:]
 	}
 
-		config.sensors = make(map[string]struct{})
+	for sensor := range strings.SplitSeq(sensorsEnvVal, ",") {
-		for sensor := range strings.SplitSeq(sensors, ",") {
 		sensor = strings.TrimSpace(sensor)
 		if sensor != "" {
 			config.sensors[sensor] = struct{}{}
@@ -61,7 +63,6 @@ func (a *Agent) newSensorConfigWithEnv(primarySensor, sysSensors, sensors string
 			}
 		}
 	}
-	}
 
 	return config
 }
@@ -69,7 +70,7 @@ func (a *Agent) newSensorConfigWithEnv(primarySensor, sysSensors, sensors string
 // updateTemperatures updates the agent with the latest sensor temperatures
 func (a *Agent) updateTemperatures(systemStats *system.Stats) {
 	// skip if sensors whitelist is set to empty string
-	if a.sensorConfig.sensors != nil && len(a.sensorConfig.sensors) == 0 {
+	if a.sensorConfig.skipCollection {
 		slog.Debug("Skipping temperature collection")
 		return
 	}
@@ -113,8 +114,8 @@ func (a *Agent) updateTemperatures(systemStats *system.Stats) {
 
 // isValidSensor checks if a sensor is valid based on the sensor name and the sensor config
 func isValidSensor(sensorName string, config *SensorConfig) bool {
-	// If no sensors configuration, everything is valid
+	// if no sensors configured, everything is valid
-	if config.sensors == nil {
+	if len(config.sensors) == 0 {
 		return true
 	}
 
@@ -123,7 +124,7 @@ func isValidSensor(sensorName string, config *SensorConfig) bool {
 		return !config.isBlacklist
 	}
 
-	// If no wildcards, return false if blacklist, true if whitelist
+	// If no wildcards, return true if blacklist, false if whitelist
 	if !config.hasWildcards {
 		return config.isBlacklist
 	}

beszel/internal/agent/sensors_test.go

@@ -97,10 +97,13 @@ func TestIsValidSensor(t *testing.T) {
 			expectedValid: true,
 		},
 		{
-			name:       "Nil sensor config",
+			name:       "No sensors configured",
 			sensorName: "any_temp",
 			config: &SensorConfig{
-				sensors: nil,
+				sensors:        map[string]struct{}{},
+				isBlacklist:    false,
+				hasWildcards:   false,
+				skipCollection: false,
 			},
 			expectedValid: true,
 		},
@@ -162,6 +165,7 @@ func TestNewSensorConfigWithEnv(t *testing.T) {
 		primarySensor  string
 		sysSensors     string
 		sensors        string
+		skipCollection bool
 		expectedConfig *SensorConfig
 	}{
 		{
@@ -172,20 +176,36 @@ func TestNewSensorConfigWithEnv(t *testing.T) {
 			expectedConfig: &SensorConfig{
 				context:        context.Background(),
 				primarySensor:  "",
-				sensors:       nil,
+				sensors:        map[string]struct{}{},
 				isBlacklist:    false,
 				hasWildcards:   false,
+				skipCollection: false,
 			},
 		},
 		{
-			name:          "Primary sensor only",
+			name:           "Explicitly set to empty string",
+			primarySensor:  "",
+			sysSensors:     "",
+			sensors:        "",
+			skipCollection: true,
+			expectedConfig: &SensorConfig{
+				context:        context.Background(),
+				primarySensor:  "",
+				sensors:        map[string]struct{}{},
+				isBlacklist:    false,
+				hasWildcards:   false,
+				skipCollection: true,
+			},
+		},
+		{
+			name:          "Primary sensor only - should create sensor map",
 			primarySensor: "cpu_temp",
 			sysSensors:    "",
 			sensors:       "",
 			expectedConfig: &SensorConfig{
 				context:       context.Background(),
 				primarySensor: "cpu_temp",
-				sensors:       nil,
+				sensors:       map[string]struct{}{},
 				isBlacklist:   false,
 				hasWildcards:  false,
 			},
@@ -238,6 +258,22 @@ func TestNewSensorConfigWithEnv(t *testing.T) {
 				hasWildcards: true,
 			},
 		},
+		{
+			name:          "Sensors with whitespace",
+			primarySensor: "cpu_temp",
+			sysSensors:    "",
+			sensors:       "cpu_*, gpu_temp",
+			expectedConfig: &SensorConfig{
+				context:       context.Background(),
+				primarySensor: "cpu_temp",
+				sensors: map[string]struct{}{
+					"cpu_*":    {},
+					"gpu_temp": {},
+				},
+				isBlacklist:  false,
+				hasWildcards: true,
+			},
+		},
 		{
 			name:          "With SYS_SENSORS path",
 			primarySensor: "cpu_temp",
@@ -256,7 +292,7 @@ func TestNewSensorConfigWithEnv(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			result := agent.newSensorConfigWithEnv(tt.primarySensor, tt.sysSensors, tt.sensors)
+			result := agent.newSensorConfigWithEnv(tt.primarySensor, tt.sysSensors, tt.sensors, tt.skipCollection)
 
 			// Check primary sensor
 			assert.Equal(t, tt.expectedConfig.primarySensor, result.primarySensor)