Stock location scan (#169)

* Add action for scanning a stock location into another location

* Adds barcode scan handler for new functionality

* Handle scanning of stock location

* Cleanup

* Refactor existing barcode scanning functions

- Will require extensive testing and validation

* Add entry to release notes

* Delete dead code

* Improved ordering based on stock quantity

* Bug fix for 'adjustStock' function

* Improve error responses for barcode scanning

* Improve error responses for barcode scanning

* Remove old debug statements

* Add some extra explanatory texts

* Icon change

* Fixes for unit tests

* Adds extra functionality for user profile manager

* Refactor barcode code - do not rely on BuildContext

* Adds initial unit testing for barcode scanning

- Work on mocking barcode data
- Add hooks for testing snackBar and audio files

* Linting fixes

* More barcode unit tests

* Cleanup unit tests for barcode

* Remove unused import

* Handle HTTPException in API

* Improvements for API unit testing

* Unit testing for scanning item into location

* Add unit test for scanning in items from a location context

* Unit test for scanning location into parent location

* Improve feedback for barcode scanning events

lib/helpers.dart

@@ -13,12 +13,37 @@ import "package:audioplayers/audioplayers.dart";
 import "package:one_context/one_context.dart";
 
 
+List<String> debug_messages = [];
+
+void clearDebugMessage() => debug_messages.clear();
+
+int debugMessageCount() => debug_messages.length;
+
+// Check if the debug log contains a given message
+bool debugContains(String msg, {bool raiseAssert = true}) {
+  bool result = false;
+
+  for (String element in debug_messages) {
+    if (element.contains(msg)) {
+      result = true;
+      break;
+    }
+  }
+
+  if (raiseAssert) {
+    assert(result);
+  }
+
+  return result;
+}
+
 /*
  * Display a debug message if we are in testing mode, or running in debug mode
  */
 void debug(dynamic msg) {
 
   if (Platform.environment.containsKey("FLUTTER_TEST")) {
+    debug_messages.add(msg.toString());
     print("DEBUG: ${msg.toString()}");
   }
 }
@@ -38,11 +63,13 @@ String simpleNumberString(double number) {
  */
 Future<void> playAudioFile(String path) async {
 
+  // Debug message for unit testing
+  debug("Playing audio file: '${path}'");
+
   if (!OneContext.hasContext) {
     return;
   }
 
   final player = AudioCache();
   player.play(path);
-
 }