Fix changing subject weights

app/lib/grades/pages/subject_settings_page/subject_settings_page_controller.dart

@@ -31,18 +31,27 @@ class SubjectSettingsPageController extends ChangeNotifier {
       return;
     }
 
+    if (subject.weightType == WeightType.perGrade) {
+      state = SubjectSettingsError(
+          'Subject "${subject.name}" (id: $subjectId) has its weightType set to ${WeightType.perGrade}. This is not supported (yet).');
+      return;
+    }
+
     _subjectName = subject.name;
     final finalGradeType = _getFinalGradeType(subject.finalGradeTypeId);
     _finalGradeTypeDisplayName = _getFinalGradeTypeDisplayName(finalGradeType);
     _finalGradeTypeIcon = _getFinalGradeTypeIcon(finalGradeType);
     _selectableGradeTypes = gradesService.getPossibleGradeTypes();
 
+    // Todo: Explain this workaround
+    _weights = IMap();
+
     if (subject.weightType == WeightType.inheritFromTerm) {
       // We show the weights from the term, but we need to copy them into the
       // subject if the user changes them.
-      _weights = _getTerm()!.gradeTypeWeightings;
+      _weights = _weights.addAll(_getTerm()!.gradeTypeWeightings);
     } else {
-      _weights = subject.gradeTypeWeights;
+      _weights = _weights.addAll(subject.gradeTypeWeights);
     }
 
     state = SubjectSettingsLoaded(view);
@@ -116,8 +125,9 @@ class SubjectSettingsPageController extends ChangeNotifier {
     // In the constructor, we already copied the weights from the term. But they
     // were only copied into the state. Now we need to copy them into the
     // database.
-    for (final gradeType in _weights.keys) {
-      subRef.changeFinalGradeType(gradeType);
+    // Todo: Use weights from term for clarity?
+    for (final entry in _weights.entries) {
+      subRef.changeGradeTypeWeight(entry.key, entry.value);
       await waitForFirestoreWriteLimit();
     }
 

app/test/grades/grades_test_common.dart

@@ -433,6 +433,7 @@ TestSubject subjectWith({
   GradeTypeId? finalGradeType,
   Design? design,
   List<ConnectedCourse> connectedCourses = const [],
+  bool ignoreWeightTypeAssertion = false,
 }) {
   final idRes = id ?? SubjectId(randomAlpha(5));
   final nameRes = name ?? idRes.value;
@@ -448,6 +449,7 @@ TestSubject subjectWith({
     gradeTypeWeights: gradeTypeWeights,
     finalGradeType: finalGradeType,
     design: design ?? Design.random(szTestRandom),
+    ignoreWeightTypeAssertion: ignoreWeightTypeAssertion,
   );
 }
 
@@ -474,7 +476,9 @@ class TestSubject {
     this.weightType,
     this.weight,
     this.finalGradeType,
+    bool ignoreWeightTypeAssertion = false,
   }) : assert(() {
+          if (ignoreWeightTypeAssertion) return true;
           // Help developers to not forget to set the weightType if
           // gradeTypeWeights or grade weights are set. This is not a hard
           // requirement by the logic, so if you need to do it anyways then you

app/test/grades/pages/subject_settings_page/subject_settings_page_controller_test.dart

@@ -0,0 +1,270 @@
+// Copyright (c) 2025 Sharezone UG (haftungsbeschränkt)
+// Licensed under the EUPL-1.2-or-later.
+//
+// You may obtain a copy of the Licence at:
+// https://joinup.ec.europa.eu/software/page/eupl
+//
+// SPDX-License-Identifier: EUPL-1.2
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:sharezone/grades/grades_service/grades_service.dart';
+import 'package:sharezone/grades/pages/subject_settings_page/subject_settings_page_controller.dart';
+
+import '../../grades_test_common.dart';
+
+void main() {
+  group('$SubjectSettingsPageController', () {
+    const termId = TermId('my-term');
+    const subjectId = SubjectId('maths');
+
+    late GradesTestController testController;
+    late TermSubjectRef subRef;
+
+    setUp(() {
+      testController = GradesTestController();
+      subRef = testController.service.term(termId).subject(subjectId);
+    });
+
+    SubjectSettingsPageController createPageController() {
+      return SubjectSettingsPageController(
+        subRef: subRef,
+        gradesService: testController.service,
+      );
+    }
+
+    test(
+        'regression test: https://github.com/SharezoneApp/sharezone-app/issues/1803\n'
+        'Correctly adds weights / overrides weights from term', () async {
+      testController.createTerm(termWith(
+        id: termId,
+        finalGradeType: GradeType.schoolReportGrade.id,
+        gradeTypeWeights: {
+          GradeType.writtenExam.id: const Weight.factor(1.5),
+        },
+        subjects: [
+          subjectWith(
+            id: subjectId,
+            weightType: WeightType.inheritFromTerm,
+            // Subjects need a grade to be really created/assigned to the term.
+            grades: [gradeWith()],
+          ),
+        ],
+      ));
+
+      var pageController = createPageController();
+      await pageController.setGradeWeight(
+          gradeTypeId: GradeType.presentation.id,
+          weight: const Weight.factor(0.5));
+
+      // This controller needs to be recreated, otherwise the bug won't show:
+      pageController = createPageController();
+      // This also can't be used instead of recreating the controller to show \
+      // the bug:
+      // await pumpEventQueue();
+
+      expect(pageController.view.weights.unlockView, {
+        GradeType.presentation.id: const Weight.factor(0.5),
+        GradeType.writtenExam.id: const Weight.factor(1.5),
+      });
+      expect(pageController.view.finalGradeTypeDisplayName,
+          GradeType.schoolReportGrade.predefinedType!.toUiString());
+    });
+
+    test('Correctly adds weights', () async {
+      testController.createTerm(termWith(
+        id: termId,
+        finalGradeType: GradeType.schoolReportGrade.id,
+        gradeTypeWeights: {
+          GradeType.writtenExam.id: const Weight.factor(1.5),
+        },
+        subjects: [
+          subjectWith(
+            id: subjectId,
+            weightType: WeightType.inheritFromTerm,
+            // Subjects need a grade to be really created/assigned to the term.
+            grades: [gradeWith()],
+          ),
+        ],
+      ));
+
+      var pageController = createPageController();
+      await pageController.setGradeWeight(
+          gradeTypeId: GradeType.presentation.id,
+          weight: const Weight.factor(0.5));
+
+      // This works:
+      expect(pageController.view.weights.unlockView, {
+        GradeType.presentation.id: const Weight.factor(0.5),
+        GradeType.writtenExam.id: const Weight.factor(1.5),
+      });
+      expect(pageController.view.finalGradeTypeDisplayName,
+          GradeType.schoolReportGrade.predefinedType!.toUiString());
+    });
+
+    test(
+        'returns final grade type from term if it is not overridden by subject',
+        () {
+      testController.createTerm(
+        termWith(
+          id: termId,
+          finalGradeType: GradeType.presentation.id,
+          subjects: [
+            subjectWith(
+              id: subjectId,
+              finalGradeType: null,
+              // Subjects need a grade to be really created/assigned to the term.
+              grades: [gradeWith()],
+            ),
+          ],
+        ),
+      );
+
+      final pageController = createPageController();
+
+      expect(pageController.view.finalGradeTypeDisplayName,
+          GradeType.presentation.predefinedType!.toUiString());
+    });
+
+    test(
+        'returns final grade type from subject if it overrides terms final grade type',
+        () {
+      testController.createTerm(
+        termWith(
+          id: termId,
+          finalGradeType: GradeType.presentation.id,
+          subjects: [
+            subjectWith(
+              id: subjectId,
+              finalGradeType: GradeType.writtenExam.id,
+              // Subjects need a grade to be really created/assigned to the term.
+              grades: [gradeWith()],
+            ),
+          ],
+        ),
+      );
+
+      final pageController = createPageController();
+
+      expect(pageController.view.finalGradeTypeDisplayName,
+          GradeType.writtenExam.predefinedType!.toUiString());
+    });
+
+    test(
+        'returns no weights if term has no default weights and subject has no weights',
+        () async {
+      testController
+          .createTerm(termWith(id: termId, gradeTypeWeights: {}, subjects: [
+        subjectWith(
+          id: subjectId,
+          gradeTypeWeights: {},
+          // Subjects need a grade to be really created/assigned to the term.
+          grades: [gradeWith()],
+        ),
+      ]));
+
+      final pageController = createPageController();
+
+      expect(pageController.view.weights, isEmpty);
+    });
+    test(
+        'returns term weights if subjects $WeightType is ${WeightType.inheritFromTerm}',
+        () async {
+      testController.createTerm(
+        termWith(
+          id: termId,
+          gradeTypeWeights: {
+            GradeType.presentation.id: const Weight.factor(0.5),
+            GradeType.oralParticipation.id: const Weight.percent(200),
+          },
+          subjects: [
+            subjectWith(
+              id: subjectId,
+              weightType: WeightType.inheritFromTerm,
+              // Should be ignored because weights are inherited from term.
+              gradeTypeWeights: {
+                GradeType.presentation.id: const Weight.factor(1.5),
+              },
+              // Ignore developer warning related to weight settings.
+              ignoreWeightTypeAssertion: true,
+              // Subjects need a grade to be really created/assigned to the term.
+              grades: [gradeWith()],
+            ),
+          ],
+        ),
+      );
+
+      final pageController = createPageController();
+
+      expect(pageController.view.weights.unlockView, {
+        GradeType.presentation.id: const Weight.factor(0.5),
+        GradeType.oralParticipation.id: const Weight.percent(200),
+      });
+    });
+    test(
+        'returns subject weights if subjects $WeightType is ${WeightType.perGradeType}',
+        () async {
+      testController.createTerm(
+        termWith(
+          id: termId,
+          gradeTypeWeights: {
+            GradeType.presentation.id: const Weight.factor(0.5),
+            GradeType.oralParticipation.id: const Weight.percent(200),
+          },
+          subjects: [
+            subjectWith(
+              id: subjectId,
+              weightType: WeightType.perGradeType,
+              // Should be ignored because weights are inherited from term.
+              gradeTypeWeights: {
+                GradeType.presentation.id: const Weight.factor(1.5),
+              },
+              // Subjects need a grade to be really created/assigned to the term.
+              grades: [gradeWith()],
+            ),
+          ],
+        ),
+      );
+
+      final pageController = createPageController();
+
+      expect(pageController.view.weights.unlockView, {
+        GradeType.presentation.id: const Weight.factor(1.5),
+      });
+    });
+    test(
+        'throws if subjects $WeightType is ${WeightType.perGrade} as we dont support it yet',
+        () async {
+      testController.createTerm(
+        termWith(
+          id: termId,
+          gradeTypeWeights: {
+            GradeType.presentation.id: const Weight.factor(0.5),
+            GradeType.oralParticipation.id: const Weight.percent(200),
+          },
+          subjects: [
+            subjectWith(
+              id: subjectId,
+              weightType: WeightType.perGrade,
+              // Subjects need a grade to be really created/assigned to the term.
+              grades: [
+                gradeWith(
+                  value: 10,
+                  gradingSystem: GradingSystem.zeroToFifteenPoints,
+                ),
+                gradeWith(
+                  value: 12,
+                  gradingSystem: GradingSystem.zeroToFifteenPoints,
+                  weight: const Weight.factor(1.5),
+                ),
+              ],
+            ),
+          ],
+        ),
+      );
+
+      final pageController = createPageController();
+
+      expect(pageController.state, isA<SubjectSettingsError>());
+    });
+  });
+}