Logging abstraction also working in tests

@@ -5,7 +5,7 @@ import 'package:get/src/state_manager/rx/rx_interface.dart';
 class GetConfig {
 class GetConfig {
   static SmartManagement smartManagement = SmartManagement.full;
   static SmartManagement smartManagement = SmartManagement.full;
   static bool isLogEnable = true;
   static bool isLogEnable = true;
-  static LogWriterCallback log;
+  static LogWriterCallback log = defaultLogWriterCallback;
   static String currentRoute;
   static String currentRoute;
 }
 }
 
 

@@ -773,7 +773,9 @@ extension GetNavigation on GetInterface {
     if (enableLog != null) {
     if (enableLog != null) {
       GetConfig.isLogEnable = enableLog;
       GetConfig.isLogEnable = enableLog;
     }
     }
-    GetConfig.log = logWriterCallback;
+    if (logWriterCallback != null) {
+      GetConfig.log = logWriterCallback;
+    }
     if (defaultPopGesture != null) {
     if (defaultPopGesture != null) {
       this.defaultPopGesture = defaultPopGesture;
       this.defaultPopGesture = defaultPopGesture;
     }
     }

@@ -204,7 +204,7 @@ class GetMaterialApp extends StatelessWidget {
 
 
           Get.config(
           Get.config(
             enableLog: enableLog ?? GetConfig.isLogEnable,
             enableLog: enableLog ?? GetConfig.isLogEnable,
-            logWriterCallback: logWriterCallback ?? defaultLogWriterCallback,
+            logWriterCallback: logWriterCallback,
             defaultTransition: defaultTransition ?? Get.defaultTransition,
             defaultTransition: defaultTransition ?? Get.defaultTransition,
             defaultOpaqueRoute: opaqueRoute ?? Get.isOpaqueRouteDefault,
             defaultOpaqueRoute: opaqueRoute ?? Get.isOpaqueRouteDefault,
             defaultPopGesture: popGesture ?? Get.isPopGestureEnable,
             defaultPopGesture: popGesture ?? Get.isPopGestureEnable,