chore: add more tests (#4949)

core/mapping/utils.go

@@ -92,6 +92,15 @@ func ValidatePtr(v reflect.Value) error {
 	return nil
 }
 
+func convertToString(val any, fullName string) (string, error) {
+	v, ok := val.(string)
+	if !ok {
+		return "", fmt.Errorf("expect string for field %s, but got type %T", fullName, val)
+	}
+
+	return v, nil
+}
+
 func convertTypeFromString(kind reflect.Kind, str string) (any, error) {
 	switch kind {
 	case reflect.Bool: