[cli] Add utility method to init float64 args

cli/cli.go

@@ -33,6 +33,21 @@ func SetIntDefaultValueFromEnv(value *int, key string, defaultValue int) error {
 	}
 	return nil
 }
+func SetFloat64DefaultValueFromEnv(value *float64, key string, defaultValue float64) error {
+	var sVal string
+	if os.Getenv(key) != "" {
+		sVal = os.Getenv(key)
+		val, err := strconv.ParseFloat(sVal, 64)
+		if err != nil {
+			log.Printf("unable to convert string to float: %v", err)
+			return err
+		}
+		*value = val
+	} else {
+		*value = defaultValue
+	}
+	return nil
+}
 
 type Part interface {
 	Start() error
@@ -71,6 +86,15 @@ func InitIntFlag(key string, defValue int) int {
 	return value
 }
 
+func InitFloat64Flag(key string, defValue float64) float64 {
+	var value float64
+	err := SetFloat64DefaultValueFromEnv(&value, key, defValue)
+	if err != nil {
+		log.Panicf("invalid value: %v", err)
+	}
+	return value
+}
+
 func Connect(uri, username, password, clientId string) (MQTT.Client, error) {
 	//create a ClientOptions struct setting the broker address, clientid, turn
 	//off trace output and set the default message handler

cli/cli_test.go

@@ -62,3 +62,39 @@ func TestSetIntDefaultValueFromEnv(t *testing.T) {
 		}
 	}
 }
+
+func TestSetFloat64DefaultValueFromEnv(t *testing.T) {
+	err := os.Setenv("KEY1", "12.2")
+	err = os.Setenv("KEY2", "12")
+	err = os.Setenv("BAD_VALUE", "bad value")
+	if err != nil {
+		t.Errorf("unable to set env value: %v", err)
+	}
+
+	cases := []struct {
+		key       string
+		defValue  float64
+		expected  float64
+		withError bool
+	}{
+		{"MISSING_KEY", 3.3, 3.3, false},
+		{"KEY1", 5, 12.2, false},
+		{"KEY2", 5, 12., false},
+		{"BAD_VALUE", 5, 0, true},
+	}
+
+	for _, c := range cases {
+		var value = 0.
+		err := SetFloat64DefaultValueFromEnv(&value, c.key, c.defValue)
+		if err != nil {
+			if !c.withError {
+				t.Errorf("SetFloat64DefaultValueFromEnv(*value, %v, %v): %v", c.key, c.defValue, err)
+			}
+		}
+		if c.withError && err == nil {
+			t.Errorf("SetFloat64DefaultValueFromEnv(*value, %v, %v): %v, wants an error", c.key, c.defValue, value)
+		} else if c.expected != value {
+			t.Errorf("SetFloat64DefaultValueFromEnv(*value, %v, %v): %v, wants %v", c.key, c.defValue, value, c.expected)
+		}
+	}
+}