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

test/barcode_test.dart

@@ -0,0 +1,160 @@
+/*
+ * Unit testing for barcode scanning functionality.
+ *
+ * As the unit testing framework cannot really "scan" barcode data,
+ * we will mock the scanned data by passing raw "barcode" data to the scanning framework.
+ */
+
+import "package:flutter_test/flutter_test.dart";
+
+import "package:inventree/api.dart";
+import "package:inventree/barcode.dart";
+import "package:inventree/helpers.dart";
+import "package:inventree/user_profile.dart";
+
+import "package:inventree/inventree/stock.dart";
+
+void main() {
+
+  // Connect to the server
+  setUpAll(() async {
+    final prf = await UserProfileDBManager().getProfileByName("Test Profile");
+
+    if (prf != null) {
+      UserProfileDBManager().deleteProfile(prf);
+    }
+
+    bool result = await UserProfileDBManager().addProfile(
+      UserProfile(
+        name: "Test Profile",
+        server: "http://localhost:12345",
+        username: "testuser",
+        password: "testpassword",
+        selected: true,
+      ),
+    );
+
+    assert(result);
+
+    assert(await UserProfileDBManager().selectProfileByName("Test Profile"));
+    assert(await InvenTreeAPI().connectToServer());
+  });
+
+  setUp(() async {
+    // Clear the debug log
+    clearDebugMessage();
+  });
+
+  group("Test BarcodeScanHandler:", () {
+    // Tests for scanning a "generic" barcode
+
+    var handler = BarcodeScanHandler();
+
+    test("Empty Barcode", () async {
+      // Handle an 'empty' barcode
+      await handler.processBarcode(null, "");
+
+      debugContains("Scanned barcode data: ''");
+      debugContains("showSnackIcon: 'Barcode scan error'");
+
+      assert(debugMessageCount() == 2);
+    });
+
+    test("Junk Data", () async {
+      // test scanning 'junk' data
+
+      await handler.processBarcode(null, "abcdefg");
+
+      debugContains("Scanned barcode data: 'abcdefg'");
+      debugContains("showSnackIcon: 'No match for barcode'");
+    });
+
+    test("Invalid StockLocation", () async {
+      // Scan an invalid stock location
+      await handler.processBarcode(null, '{"stocklocation": 999999}');
+
+      debugContains("Scanned barcode data: '{\"stocklocation\": 999999}'");
+      debugContains("showSnackIcon: 'No match for barcode'");
+      assert(debugMessageCount() == 2);
+    });
+
+  });
+
+  group("Test StockItemScanIntoLocationHandler:", () {
+    // Tests for scanning a stock item into a location
+
+    test("Scan Into Location", () async {
+
+      final item = await InvenTreeStockItem().get(1) as InvenTreeStockItem?;
+
+      assert(item != null);
+      assert(item!.pk == 1);
+
+      var handler = StockItemScanIntoLocationHandler(item!);
+
+      await handler.processBarcode(null, '{"stocklocation": 7}');
+      // Check the location has been updated
+      await item.reload();
+      assert(item.locationId == 7);
+
+      debugContains("Scanned stock location 7");
+
+      // Scan into a new location
+      await handler.processBarcode(null, '{"stocklocation": 1}');
+      await item.reload();
+      assert(item.locationId == 1);
+
+    });
+  });
+
+  group("Test StockLocationScanInItemsHandler:", () {
+    // Tests for scanning items into a stock location
+
+    test("Scan In Items", () async {
+      final location = await InvenTreeStockLocation().get(1) as InvenTreeStockLocation?;
+
+      assert(location != null);
+      assert(location!.pk == 1);
+
+      var handler = StockLocationScanInItemsHandler(location!);
+
+      // Scan multiple items into this location
+      for (int id in [1, 2, 11]) {
+        await handler.processBarcode(null, '{"stockitem": ${id}}');
+
+        var item = await InvenTreeStockItem().get(id) as InvenTreeStockItem?;
+
+        assert(item != null);
+        assert(item!.pk == id);
+        assert(item!.locationId == 1);
+      }
+
+    });
+  });
+
+  group("Test ScanParentLocationHandler:", () {
+    // Tests for scanning a location into a parent location
+
+    test("Scan Parent", () async {
+      final location = await InvenTreeStockLocation().get(7) as InvenTreeStockLocation?;
+
+      assert(location != null);
+      assert(location!.pk == 7);
+      assert(location!.parentId == 4);
+
+      var handler = ScanParentLocationHandler(location!);
+
+      // Scan into new parent location
+      await handler.processBarcode(null, '{"stocklocation": 1}');
+      await location.reload();
+      assert(location.parentId == 1);
+
+      // Scan back into old parent location
+      await handler.processBarcode(null, '{"stocklocation": 4}');
+      await location.reload();
+      assert(location.parentId == 4);
+
+      debugContains("showSnackIcon: 'Scanned into location'");
+    });
+  });
+}