From 3c9e9950c430b93074f403900595654fa119d435 Mon Sep 17 00:00:00 2001
From: Jonas Sander <29028262+Jonas-Sander@users.noreply.github.com>
Date: Wed, 21 Aug 2024 11:42:35 +0200
Subject: [PATCH 1/7] Add and implement: 'Setting a grade weight to a negative
 number throws an $ArgumentError'.

---
 .../grades/grades_service/grades_service.dart |  2 ++
 app/lib/grades/grades_service/src/term.dart   |  3 ++
 app/test/grades/grades_test.dart              | 34 +++++++++++++++++++
 3 files changed, 39 insertions(+)

diff --git a/app/lib/grades/grades_service/grades_service.dart b/app/lib/grades/grades_service/grades_service.dart
index 023409151..eb04a7f2f 100644
--- a/app/lib/grades/grades_service/grades_service.dart
+++ b/app/lib/grades/grades_service/grades_service.dart
@@ -758,6 +758,8 @@ class Weight extends Equatable {
   @override
   List<Object?> get props => [asFactor];
 
+  bool get isNegative => asFactor < 0;
+
   const Weight.percent(num percent) : asFactor = percent / 100;
   const Weight.factor(this.asFactor);
   static const zero = Weight.factor(0);
diff --git a/app/lib/grades/grades_service/src/term.dart b/app/lib/grades/grades_service/src/term.dart
index 52a4614ea..066910933 100644
--- a/app/lib/grades/grades_service/src/term.dart
+++ b/app/lib/grades/grades_service/src/term.dart
@@ -549,6 +549,9 @@ class GradeModel extends Equatable {
   }) : assert(originalInput is String || originalInput is num);
 
   GradeModel changeWeight(Weight weight) {
+    if (weight.isNegative) {
+      throw ArgumentError('Weight must be greater than or equal to 0');
+    }
     return copyWith(weight: weight, takenIntoAccount: weight.asFactor > 0);
   }
 
diff --git a/app/test/grades/grades_test.dart b/app/test/grades/grades_test.dart
index 3f102d23a..dc1d735fd 100644
--- a/app/test/grades/grades_test.dart
+++ b/app/test/grades/grades_test.dart
@@ -302,6 +302,40 @@ void main() {
               .asDouble,
           expected);
     });
+    test('Setting a grade weight to a negative number throws an $ArgumentError',
+        () {
+      final controller = GradesTestController();
+
+      final term = termWith(
+        id: const TermId('term1'),
+        subjects: [
+          subjectWith(
+            id: const SubjectId('Mathe'),
+            name: 'Mathe',
+            weightType: WeightType.perGrade,
+            grades: [
+              gradeWith(
+                id: const GradeId('grade1'),
+                value: 1.0,
+                weight: const Weight.factor(0.2),
+              ),
+            ],
+          ),
+        ],
+      );
+      controller.createTerm(term);
+
+      expect(
+        () => controller.changeGradeWeightsForSubject(
+          termId: const TermId('term1'),
+          subjectId: const SubjectId('Mathe'),
+          weights: {
+            const GradeId('grade1'): const Weight.factor(-0.1),
+          },
+        ),
+        throwsA(isA<ArgumentError>()),
+      );
+    });
     test(
         'grades for a subject will be weighted by the settings in term by default',
         () {

From 13a366e89305d00b9da16fab6e2a15e6c9a19521 Mon Sep 17 00:00:00 2001
From: Jonas Sander <29028262+Jonas-Sander@users.noreply.github.com>
Date: Wed, 21 Aug 2024 11:48:04 +0200
Subject: [PATCH 2/7] Add and implement: 'Setting a grade type weight for a
 subject to a negative number throws an $ArgumentError'

---
 app/lib/grades/grades_service/src/term.dart |  3 ++
 app/test/grades/grades_test.dart            | 39 +++++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/app/lib/grades/grades_service/src/term.dart b/app/lib/grades/grades_service/src/term.dart
index 066910933..f7a4d31c3 100644
--- a/app/lib/grades/grades_service/src/term.dart
+++ b/app/lib/grades/grades_service/src/term.dart
@@ -434,6 +434,9 @@ class SubjectModel extends Equatable {
 
   SubjectModel changeGradeTypeWeight(GradeTypeId gradeType,
       {required Weight weight}) {
+    if (weight.isNegative) {
+      throw ArgumentError('Weight must be greater than or equal to 0');
+    }
     return copyWith(
         gradeTypeWeightings: gradeTypeWeightings.add(gradeType, weight));
   }
diff --git a/app/test/grades/grades_test.dart b/app/test/grades/grades_test.dart
index dc1d735fd..be7b30bf5 100644
--- a/app/test/grades/grades_test.dart
+++ b/app/test/grades/grades_test.dart
@@ -336,6 +336,45 @@ void main() {
         throwsA(isA<ArgumentError>()),
       );
     });
+    test(
+        'Setting a grade type weight for a subject to a negative number throws an $ArgumentError',
+        () {
+      final controller = GradesTestController();
+
+      final term = termWith(
+        id: const TermId('term1'),
+        subjects: [
+          subjectWith(
+            id: const SubjectId('Mathe'),
+            name: 'Mathe',
+            weightType: WeightType.perGradeType,
+            gradeTypeWeights: {
+              GradeType.presentation.id: const Weight.factor(1),
+            },
+            grades: [
+              gradeWith(
+                id: const GradeId('grade1'),
+                type: GradeType.presentation.id,
+                value: 1.0,
+                weight: const Weight.factor(0.2),
+              ),
+            ],
+          ),
+        ],
+      );
+      controller.createTerm(term);
+
+      expect(
+        () => controller.changeTermWeightsForSubject(
+          termId: const TermId('term1'),
+          subjectId: const SubjectId('Mathe'),
+          gradeTypeWeights: {
+            GradeType.presentation.id: const Weight.factor(-0.1),
+          },
+        ),
+        throwsA(isA<ArgumentError>()),
+      );
+    });
     test(
         'grades for a subject will be weighted by the settings in term by default',
         () {

From 2e472ece2379ae06750581b8d471310bf0976783 Mon Sep 17 00:00:00 2001
From: Jonas Sander <29028262+Jonas-Sander@users.noreply.github.com>
Date: Wed, 21 Aug 2024 12:20:01 +0200
Subject: [PATCH 3/7] Add and implement: 'Setting a grade type weight for a
 term to a negative number throws an $ArgumentError'

---
 app/lib/grades/grades_service/src/term.dart |  3 +++
 app/test/grades/grades_test.dart            | 30 +++++++++++++++++++++
 app/test/grades/grades_test_common.dart     |  8 ++++++
 3 files changed, 41 insertions(+)

diff --git a/app/lib/grades/grades_service/src/term.dart b/app/lib/grades/grades_service/src/term.dart
index f7a4d31c3..77fbecb03 100644
--- a/app/lib/grades/grades_service/src/term.dart
+++ b/app/lib/grades/grades_service/src/term.dart
@@ -152,6 +152,9 @@ class TermModel extends Equatable {
 
   TermModel changeWeightingOfGradeType(GradeTypeId type,
       {required Weight weight}) {
+    if (weight.isNegative) {
+      throw ArgumentError('Weight must be greater than or equal to 0');
+    }
     final newWeights = gradeTypeWeightings.add(type, weight);
     final newSubjects = subjects.map((s) {
       final newSubject = s.copyWith(gradeTypeWeightingsFromTerm: newWeights);
diff --git a/app/test/grades/grades_test.dart b/app/test/grades/grades_test.dart
index be7b30bf5..a1f42b499 100644
--- a/app/test/grades/grades_test.dart
+++ b/app/test/grades/grades_test.dart
@@ -375,6 +375,36 @@ void main() {
         throwsA(isA<ArgumentError>()),
       );
     });
+    test(
+        'Setting a grade type weight for a term to a negative number throws an $ArgumentError',
+        () {
+      final controller = GradesTestController();
+
+      final term = termWith(
+        id: const TermId('term1'),
+        gradeTypeWeights: {
+          GradeType.presentation.id: const Weight.factor(1),
+        },
+        subjects: [
+          subjectWith(
+            grades: [
+              gradeWith(type: GradeType.presentation.id, value: 1.0),
+            ],
+          ),
+        ],
+      );
+      controller.createTerm(term);
+
+      expect(
+        () => controller.changeGradeTypeWeightForTerm(
+          termId: const TermId('term1'),
+          gradeTypeWeights: {
+            GradeType.presentation.id: const Weight.factor(-0.1),
+          },
+        ),
+        throwsA(isA<ArgumentError>()),
+      );
+    });
     test(
         'grades for a subject will be weighted by the settings in term by default',
         () {
diff --git a/app/test/grades/grades_test_common.dart b/app/test/grades/grades_test_common.dart
index 6b22334fc..c907bcbfd 100644
--- a/app/test/grades/grades_test_common.dart
+++ b/app/test/grades/grades_test_common.dart
@@ -193,6 +193,14 @@ class GradesTestController {
     }
   }
 
+  void changeGradeTypeWeightForTerm(
+      {required TermId termId,
+      required Map<GradeTypeId, Weight> gradeTypeWeights}) {
+    for (var e in gradeTypeWeights.entries) {
+      service.term(termId).changeGradeTypeWeight(e.key, e.value);
+    }
+  }
+
   void changeFinalGradeTypeForSubject(
       {required TermId termId,
       required SubjectId subjectId,

From 0167e86d92ccc18430f2f8380aae95df10d0feb6 Mon Sep 17 00:00:00 2001
From: Jonas Sander <29028262+Jonas-Sander@users.noreply.github.com>
Date: Wed, 21 Aug 2024 12:25:29 +0200
Subject: [PATCH 4/7] Add and implement: 'Setting a subject weight for a term
 to a negative number throws an $ArgumentError'

---
 app/lib/grades/grades_service/src/term.dart |  3 +++
 app/test/grades/grades_test.dart            | 26 +++++++++++++++++++++
 app/test/grades/grades_test_common.dart     |  8 +++++++
 3 files changed, 37 insertions(+)

diff --git a/app/lib/grades/grades_service/src/term.dart b/app/lib/grades/grades_service/src/term.dart
index 77fbecb03..d3c85a124 100644
--- a/app/lib/grades/grades_service/src/term.dart
+++ b/app/lib/grades/grades_service/src/term.dart
@@ -250,6 +250,9 @@ class TermModel extends Equatable {
   }
 
   TermModel changeWeighting(SubjectId id, Weight newWeight) {
+    if (newWeight.isNegative) {
+      throw ArgumentError('Weight must be greater than or equal to 0');
+    }
     final subject = subjects.firstWhere((s) => s.id == id);
     final newSubject = subject.copyWith(
       weightingForTermGrade: newWeight,
diff --git a/app/test/grades/grades_test.dart b/app/test/grades/grades_test.dart
index a1f42b499..05e5c3fef 100644
--- a/app/test/grades/grades_test.dart
+++ b/app/test/grades/grades_test.dart
@@ -405,6 +405,32 @@ void main() {
         throwsA(isA<ArgumentError>()),
       );
     });
+    test(
+        'Setting a subject weight for a term to a negative number throws an $ArgumentError',
+        () {
+      final controller = GradesTestController();
+
+      final term = termWith(
+        id: const TermId('term1'),
+        subjects: [
+          subjectWith(
+            id: const SubjectId('Mathe'),
+            grades: [gradeWith()],
+          ),
+        ],
+      );
+      controller.createTerm(term);
+
+      expect(
+        () => controller.changeTermSubjectWeights(
+          termId: const TermId('term1'),
+          subjectWeights: {
+            const SubjectId('Mathe'): const Weight.factor(-0.1),
+          },
+        ),
+        throwsA(isA<ArgumentError>()),
+      );
+    });
     test(
         'grades for a subject will be weighted by the settings in term by default',
         () {
diff --git a/app/test/grades/grades_test_common.dart b/app/test/grades/grades_test_common.dart
index c907bcbfd..5274b5e9f 100644
--- a/app/test/grades/grades_test_common.dart
+++ b/app/test/grades/grades_test_common.dart
@@ -333,6 +333,14 @@ class GradesTestController {
       {required TermId termId, required WeightDisplayType weightDisplayType}) {
     service.term(termId).changeWeightDisplayType(weightDisplayType);
   }
+
+  void changeTermSubjectWeights(
+      {required TermId termId,
+      required Map<SubjectId, Weight> subjectWeights}) {
+    for (var e in subjectWeights.entries) {
+      service.term(termId).subject(e.key).changeWeightForTermGrade(e.value);
+    }
+  }
 }
 
 TestTerm termWith({

From 27ef6ca5edfe8dc8de824851956976a1bd69674d Mon Sep 17 00:00:00 2001
From: Jonas Sander <29028262+Jonas-Sander@users.noreply.github.com>
Date: Wed, 21 Aug 2024 12:56:31 +0200
Subject: [PATCH 5/7] Create and use `NonNegativeWeight` class.

---
 .../grades/grades_service/grades_service.dart | 11 ++-
 .../grades_service/src/grades_repository.dart | 23 ++++--
 .../src/grades_service_internal.dart          | 13 ++--
 app/lib/grades/grades_service/src/term.dart   | 76 +++++++++++--------
 app/test/grades/grades_repository_test.dart   | 32 ++++----
 5 files changed, 93 insertions(+), 62 deletions(-)

diff --git a/app/lib/grades/grades_service/grades_service.dart b/app/lib/grades/grades_service/grades_service.dart
index eb04a7f2f..43ceec4d4 100644
--- a/app/lib/grades/grades_service/grades_service.dart
+++ b/app/lib/grades/grades_service/grades_service.dart
@@ -752,11 +752,9 @@ class ConnectedCourse extends Equatable {
   });
 }
 
-class Weight extends Equatable {
+class Weight {
   final num asFactor;
   num get asPercentage => asFactor * 100;
-  @override
-  List<Object?> get props => [asFactor];
 
   bool get isNegative => asFactor < 0;
 
@@ -768,4 +766,11 @@ class Weight extends Equatable {
   String toString() {
     return 'Weight($asFactor / $asPercentage%)';
   }
+
+  @override
+  bool operator ==(Object other) =>
+      identical(this, other) || other is Weight && other.asFactor == asFactor;
+
+  @override
+  int get hashCode => asFactor.hashCode;
 }
diff --git a/app/lib/grades/grades_service/src/grades_repository.dart b/app/lib/grades/grades_service/src/grades_repository.dart
index 7f809dc94..7830e56c3 100644
--- a/app/lib/grades/grades_service/src/grades_repository.dart
+++ b/app/lib/grades/grades_service/src/grades_repository.dart
@@ -205,8 +205,8 @@ class FirestoreGradesStateRepository extends GradesStateRepository {
                   ?.gradeComposition
                   .gradeWeights
                   .map((key, value) =>
-                      MapEntry(key, value.toWeight()))[dto.id] ??
-              const Weight.factor(1),
+                      MapEntry(key, value.toNonNegativeWeight()))[dto.id] ??
+              NonNegativeWeight.factor(1),
         );
       },
     ).toIList();
@@ -259,14 +259,16 @@ class FirestoreGradesStateRepository extends GradesStateRepository {
         isFinalGradeTypeOverridden:
             termSubject.finalGradeType != subTerm.finalGradeTypeId,
         gradeTypeWeightings: termSubject.gradeComposition.gradeTypeWeights
-            .map((key, value) => MapEntry(GradeTypeId(key), value.toWeight()))
+            .map((key, value) =>
+                MapEntry(GradeTypeId(key), value.toNonNegativeWeight()))
             .toIMap(),
         gradeTypeWeightingsFromTerm: subTerm.gradeTypeWeights
-            .map((key, value) => MapEntry(GradeTypeId(key), value.toWeight()))
+            .map((key, value) =>
+                MapEntry(GradeTypeId(key), value.toNonNegativeWeight()))
             .toIMap(),
         weightingForTermGrade:
-            subTerm.subjectWeights[subject.id.value]?.toWeight() ??
-                const Weight.factor(1),
+            subTerm.subjectWeights[subject.id.value]?.toNonNegativeWeight() ??
+                NonNegativeWeight.factor(1),
         grades: grades
             .where((grade) =>
                 grade.subjectId == subject.id && grade.termId.value == termId)
@@ -295,7 +297,7 @@ class FirestoreGradesStateRepository extends GradesStateRepository {
             // Change both to num
             gradeTypeWeightings: dto.gradeTypeWeights
                 .map((key, value) =>
-                    MapEntry(GradeTypeId(key), value.toWeight()))
+                    MapEntry(GradeTypeId(key), value.toNonNegativeWeight()))
                 .toIMap(),
           ),
         )
@@ -385,6 +387,13 @@ class WeightDto {
     );
   }
 
+  NonNegativeWeight toNonNegativeWeight() {
+    return switch (type) {
+      _WeightNumberType.factor => NonNegativeWeight.factor(value),
+      _WeightNumberType.percent => NonNegativeWeight.percent(value),
+    };
+  }
+
   Weight toWeight() {
     return switch (type) {
       _WeightNumberType.factor => Weight.factor(value),
diff --git a/app/lib/grades/grades_service/src/grades_service_internal.dart b/app/lib/grades/grades_service/src/grades_service_internal.dart
index 1c842f58a..aac99512c 100644
--- a/app/lib/grades/grades_service/src/grades_service_internal.dart
+++ b/app/lib/grades/grades_service/src/grades_service_internal.dart
@@ -216,7 +216,7 @@ class _GradesServiceInternal {
       newTerm = newTerm.addSubject(subject);
     }
 
-    newTerm = newTerm.changeWeighting(id, weight);
+    newTerm = newTerm.changeWeighting(id, weight.toNonNegativeWeightOrThrow());
     _updateTerm(newTerm);
   }
 
@@ -234,8 +234,8 @@ class _GradesServiceInternal {
     required GradeTypeId gradeType,
     required Weight weight,
   }) {
-    final newTerm = _term(termId)
-        .changeWeightingOfGradeTypeInSubject(id, gradeType, weight);
+    final newTerm = _term(termId).changeWeightingOfGradeTypeInSubject(
+        id, gradeType, weight.toNonNegativeWeightOrThrow());
     _updateTerm(newTerm);
   }
 
@@ -326,7 +326,8 @@ class _GradesServiceInternal {
         .subjects
         .where((element) => element.grades.any((grade) => grade.id == id))
         .first;
-    final newTerm = _term(termId).changeWeightOfGrade(id, subject.id, weight);
+    final newTerm = _term(termId).changeWeightOfGrade(
+        id, subject.id, weight.toNonNegativeWeightOrThrow());
 
     _updateTerm(newTerm);
   }
@@ -341,8 +342,8 @@ class _GradesServiceInternal {
       {required TermId termId,
       required GradeTypeId gradeType,
       required Weight weight}) {
-    final newTerm =
-        _term(termId).changeWeightingOfGradeType(gradeType, weight: weight);
+    final newTerm = _term(termId).changeWeightingOfGradeType(gradeType,
+        weight: weight.toNonNegativeWeightOrThrow());
     _updateTerm(newTerm);
   }
 
diff --git a/app/lib/grades/grades_service/src/term.dart b/app/lib/grades/grades_service/src/term.dart
index d3c85a124..783574209 100644
--- a/app/lib/grades/grades_service/src/term.dart
+++ b/app/lib/grades/grades_service/src/term.dart
@@ -15,7 +15,7 @@ class TermModel extends Equatable {
   final TermId id;
   final DateTime? createdOn;
   final IList<SubjectModel> subjects;
-  final IMap<GradeTypeId, Weight> gradeTypeWeightings;
+  final IMap<GradeTypeId, NonNegativeWeight> gradeTypeWeightings;
   final GradingSystemModel gradingSystem;
   final GradeTypeId finalGradeType;
   final bool isActiveTerm;
@@ -96,7 +96,7 @@ class TermModel extends Equatable {
   TermModel _copyWith({
     TermId? id,
     IList<SubjectModel>? subjects,
-    IMap<GradeTypeId, Weight>? gradeTypeWeightings,
+    IMap<GradeTypeId, NonNegativeWeight>? gradeTypeWeightings,
     WeightDisplayType? weightDisplayType,
     GradeTypeId? finalGradeType,
     bool? isActiveTerm,
@@ -151,10 +151,7 @@ class TermModel extends Equatable {
   }
 
   TermModel changeWeightingOfGradeType(GradeTypeId type,
-      {required Weight weight}) {
-    if (weight.isNegative) {
-      throw ArgumentError('Weight must be greater than or equal to 0');
-    }
+      {required NonNegativeWeight weight}) {
     final newWeights = gradeTypeWeightings.add(type, weight);
     final newSubjects = subjects.map((s) {
       final newSubject = s.copyWith(gradeTypeWeightingsFromTerm: newWeights);
@@ -239,7 +236,7 @@ class TermModel extends Equatable {
       gradingSystem: gradingSystem,
       takenIntoAccount: grade.takeIntoAccount,
       gradeType: grade.type,
-      weight: const Weight.factor(1),
+      weight: NonNegativeWeight.factor(1),
       title: grade.title,
       details: grade.details,
     );
@@ -249,10 +246,7 @@ class TermModel extends Equatable {
     return subjects.any((s) => s.hasGrade(gradeId));
   }
 
-  TermModel changeWeighting(SubjectId id, Weight newWeight) {
-    if (newWeight.isNegative) {
-      throw ArgumentError('Weight must be greater than or equal to 0');
-    }
+  TermModel changeWeighting(SubjectId id, NonNegativeWeight newWeight) {
     final subject = subjects.firstWhere((s) => s.id == id);
     final newSubject = subject.copyWith(
       weightingForTermGrade: newWeight,
@@ -264,7 +258,7 @@ class TermModel extends Equatable {
   }
 
   TermModel changeWeightingOfGradeTypeInSubject(
-      SubjectId id, GradeTypeId gradeType, Weight weight) {
+      SubjectId id, GradeTypeId gradeType, NonNegativeWeight weight) {
     final subject = subjects.firstWhere((s) => s.id == id);
     final newSubject = subject.changeGradeTypeWeight(gradeType, weight: weight);
 
@@ -284,7 +278,7 @@ class TermModel extends Equatable {
   }
 
   TermModel changeWeightOfGrade(
-      GradeId id, SubjectId subjectId, Weight weight) {
+      GradeId id, SubjectId subjectId, NonNegativeWeight weight) {
     final subject = subjects.firstWhere((s) => s.id == subjectId);
     final newSubject = subject.copyWith(
       grades: subject.grades.replaceFirstWhere(
@@ -348,9 +342,9 @@ class SubjectModel extends Equatable {
   final IList<GradeModel> grades;
   final GradeTypeId finalGradeType;
   final bool isFinalGradeTypeOverridden;
-  final Weight weightingForTermGrade;
-  final IMap<GradeTypeId, Weight> gradeTypeWeightings;
-  final IMap<GradeTypeId, Weight> gradeTypeWeightingsFromTerm;
+  final NonNegativeWeight weightingForTermGrade;
+  final IMap<GradeTypeId, NonNegativeWeight> gradeTypeWeightings;
+  final IMap<GradeTypeId, NonNegativeWeight> gradeTypeWeightingsFromTerm;
   final WeightType weightType;
   final String abbreviation;
   final Design design;
@@ -391,10 +385,11 @@ class SubjectModel extends Equatable {
     this.connectedCourses = const IListConst([]),
     this.isFinalGradeTypeOverridden = false,
     this.grades = const IListConst([]),
-    this.weightingForTermGrade = const Weight.factor(1),
+    NonNegativeWeight? weightingForTermGrade,
     this.gradeTypeWeightings = const IMapConst({}),
     this.gradeTypeWeightingsFromTerm = const IMapConst({}),
-  }) {
+  }) : weightingForTermGrade =
+            weightingForTermGrade ?? NonNegativeWeight.factor(1) {
     gradeVal = _getGradeVal();
   }
 
@@ -439,10 +434,7 @@ class SubjectModel extends Equatable {
   }
 
   SubjectModel changeGradeTypeWeight(GradeTypeId gradeType,
-      {required Weight weight}) {
-    if (weight.isNegative) {
-      throw ArgumentError('Weight must be greater than or equal to 0');
-    }
+      {required NonNegativeWeight weight}) {
     return copyWith(
         gradeTypeWeightings: gradeTypeWeightings.add(gradeType, weight));
   }
@@ -476,10 +468,10 @@ class SubjectModel extends Equatable {
     IList<GradeModel>? grades,
     GradeTypeId? finalGradeType,
     bool? isFinalGradeTypeOverridden,
-    Weight? weightingForTermGrade,
+    NonNegativeWeight? weightingForTermGrade,
     GradingSystemModel? gradingSystem,
-    IMap<GradeTypeId, Weight>? gradeTypeWeightings,
-    IMap<GradeTypeId, Weight>? gradeTypeWeightingsFromTerm,
+    IMap<GradeTypeId, NonNegativeWeight>? gradeTypeWeightings,
+    IMap<GradeTypeId, NonNegativeWeight>? gradeTypeWeightingsFromTerm,
     WeightType? weightType,
     IList<ConnectedCourse>? connectedCourses,
     DateTime? createdOn,
@@ -515,7 +507,7 @@ class GradeModel extends Equatable {
   final GradingSystemModel gradingSystem;
   final GradeTypeId gradeType;
   final bool takenIntoAccount;
-  final Weight weight;
+  final NonNegativeWeight weight;
   final Date date;
   final String title;
   final String? details;
@@ -557,10 +549,7 @@ class GradeModel extends Equatable {
     this.createdOn,
   }) : assert(originalInput is String || originalInput is num);
 
-  GradeModel changeWeight(Weight weight) {
-    if (weight.isNegative) {
-      throw ArgumentError('Weight must be greater than or equal to 0');
-    }
+  GradeModel changeWeight(NonNegativeWeight weight) {
     return copyWith(weight: weight, takenIntoAccount: weight.asFactor > 0);
   }
 
@@ -573,7 +562,7 @@ class GradeModel extends Equatable {
     GradingSystemModel? gradingSystem,
     GradeTypeId? gradeType,
     bool? takenIntoAccount,
-    Weight? weight,
+    NonNegativeWeight? weight,
     String? title,
     String? details,
     DateTime? createdOn,
@@ -596,3 +585,28 @@ class GradeModel extends Equatable {
     );
   }
 }
+
+/// A [Weight] that is guaranteed to be non-negative.
+///
+/// Used so that we can enforce with the type system that a weight is non-negative
+/// This is better than just checking for non-negativity in the code because it
+/// makes it impossible to create a negative weight in the first place.
+class NonNegativeWeight extends Weight {
+  NonNegativeWeight.fromWeight(Weight weight) : super.factor(weight.asFactor);
+  NonNegativeWeight.factor(num factor) : super.factor(factor) {
+    if (factor < 0) {
+      throw ArgumentError('Weight must be non-negative');
+    }
+  }
+  NonNegativeWeight.percent(num percent) : super.percent(percent) {
+    if (percent < 0) {
+      throw ArgumentError('Weight must be non-negative');
+    }
+  }
+}
+
+extension on Weight {
+  NonNegativeWeight toNonNegativeWeightOrThrow() {
+    return NonNegativeWeight.fromWeight(this);
+  }
+}
diff --git a/app/test/grades/grades_repository_test.dart b/app/test/grades/grades_repository_test.dart
index b85ca6a4b..37da2d8fc 100644
--- a/app/test/grades/grades_repository_test.dart
+++ b/app/test/grades/grades_repository_test.dart
@@ -277,14 +277,14 @@ void main() {
       term0110.changeWeightDisplayType(WeightDisplayType.percent);
 
       term0210.changeGradeTypeWeight(
-          GradeType.vocabularyTest.id, const Weight.factor(1.5));
+          GradeType.vocabularyTest.id, NonNegativeWeight.factor(1.5));
 
       term0210.subject(const SubjectId('mathe'))
         ..changeGradeTypeWeight(const GradeTypeId('my-custom-grade-type'),
-            const Weight.percent(200))
-        ..grade(GradeId('grade-1')).changeWeight(const Weight.factor(0.5))
+            NonNegativeWeight.percent(200))
+        ..grade(GradeId('grade-1')).changeWeight(NonNegativeWeight.factor(0.5))
         ..changeWeightType(WeightType.perGrade)
-        ..changeWeightForTermGrade(const Weight.percent(250));
+        ..changeWeightForTermGrade(NonNegativeWeight.percent(250));
 
       final res = repository.data;
 
@@ -536,7 +536,7 @@ void main() {
                     gradingSystem: GradingSystemModel.zeroToFifteenPoints,
                     gradeType: const GradeTypeId('my-custom-grade-type'),
                     takenIntoAccount: true,
-                    weight: const Weight.factor(0.5),
+                    weight: NonNegativeWeight.factor(0.5),
                     date: Date('2024-10-02'),
                     title: 'hallo',
                     details: 'hello',
@@ -555,8 +555,8 @@ void main() {
                     gradingSystem: GradingSystemModel.zeroToFifteenPoints,
                     gradeType: const GradeTypeId('vocabulary-test'),
                     takenIntoAccount: true,
-                    weight: const Weight.factor(1),
-                    // weight: const Weight.factor(0.5),
+                    weight: NonNegativeWeight.factor(1),
+                    // weight: NonNegativeWeight.factor(0.5),
                     // date: Date('2024-10-02'),
                     date: Date('2024-10-03'),
                     title: 'abcdef',
@@ -565,13 +565,14 @@ void main() {
                 ]),
                 finalGradeType: const GradeTypeId('school-report-grade'),
                 isFinalGradeTypeOverridden: false,
-                weightingForTermGrade: const Weight.factor(2.5),
+                weightingForTermGrade: NonNegativeWeight.factor(2.5),
                 gradeTypeWeightings: IMapConst({
                   const GradeTypeId('my-custom-grade-type'):
-                      const Weight.factor(2.0)
+                      NonNegativeWeight.factor(2.0)
                 }),
                 gradeTypeWeightingsFromTerm: IMapConst({
-                  const GradeTypeId('vocabulary-test'): const Weight.factor(1.5)
+                  const GradeTypeId('vocabulary-test'):
+                      NonNegativeWeight.factor(1.5)
                 }),
                 weightType: WeightType.perGrade,
                 abbreviation: 'M',
@@ -589,8 +590,9 @@ void main() {
               )
             ],
           ),
-          gradeTypeWeightings: IMapConst(
-              {const GradeTypeId('vocabulary-test'): const Weight.factor(1.5)}),
+          gradeTypeWeightings: IMapConst({
+            const GradeTypeId('vocabulary-test'): NonNegativeWeight.factor(1.5)
+          }),
           gradingSystem: GradingSystemModel.zeroToFifteenPoints,
           finalGradeType: const GradeTypeId('school-report-grade'),
           isActiveTerm: true,
@@ -620,7 +622,7 @@ void main() {
                     gradingSystem: GradingSystemModel.oneToSixWithPlusAndMinus,
                     gradeType: const GradeTypeId('my-custom-grade-type'),
                     takenIntoAccount: false,
-                    weight: const Weight.factor(1),
+                    weight: NonNegativeWeight.factor(1),
                     date: Date('2024-10-16'),
                     title: 'hallo',
                     details: 'ollah',
@@ -638,7 +640,7 @@ void main() {
                     gradingSystem: GradingSystemModel.austrianBehaviouralGrades,
                     gradeType: const GradeTypeId('oral-participation'),
                     takenIntoAccount: true,
-                    weight: const Weight.factor(1),
+                    weight: NonNegativeWeight.factor(1),
                     date: Date('2024-10-18'),
                     title: 'Beep boop',
                     details: 'robot noises',
@@ -647,7 +649,7 @@ void main() {
               ),
               finalGradeType: const GradeTypeId('oral-participation'),
               isFinalGradeTypeOverridden: true,
-              weightingForTermGrade: const Weight.factor(1),
+              weightingForTermGrade: NonNegativeWeight.factor(1),
               gradeTypeWeightings: const IMapConst({}),
               gradeTypeWeightingsFromTerm: const IMapConst({}),
               weightType: WeightType.inheritFromTerm,

From 90b74d4e0e8ab10d1dacaac6cd9ea49d465c62d6 Mon Sep 17 00:00:00 2001
From: Jonas Sander <29028262+Jonas-Sander@users.noreply.github.com>
Date: Wed, 21 Aug 2024 13:03:02 +0200
Subject: [PATCH 6/7] Remove redundant code in grades_test.dart

---
 app/test/grades/grades_test.dart | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/app/test/grades/grades_test.dart b/app/test/grades/grades_test.dart
index 07e4b129b..10f17b06d 100644
--- a/app/test/grades/grades_test.dart
+++ b/app/test/grades/grades_test.dart
@@ -311,12 +311,10 @@ void main() {
         subjects: [
           subjectWith(
             id: const SubjectId('Mathe'),
-            name: 'Mathe',
             weightType: WeightType.perGrade,
             grades: [
               gradeWith(
                 id: const GradeId('grade1'),
-                value: 1.0,
                 weight: const Weight.factor(0.2),
               ),
             ],
@@ -346,18 +344,12 @@ void main() {
         subjects: [
           subjectWith(
             id: const SubjectId('Mathe'),
-            name: 'Mathe',
             weightType: WeightType.perGradeType,
             gradeTypeWeights: {
               GradeType.presentation.id: const Weight.factor(1),
             },
             grades: [
-              gradeWith(
-                id: const GradeId('grade1'),
-                type: GradeType.presentation.id,
-                value: 1.0,
-                weight: const Weight.factor(0.2),
-              ),
+              gradeWith(type: GradeType.presentation.id),
             ],
           ),
         ],

From 1246bbe303ab7217a220e2c90891649d402a6005 Mon Sep 17 00:00:00 2001
From: Jonas Sander <29028262+Jonas-Sander@users.noreply.github.com>
Date: Wed, 21 Aug 2024 13:15:32 +0200
Subject: [PATCH 7/7] Fix `NonNegativeWeight.fromWeight` constructor

---
 app/lib/grades/grades_service/src/term.dart | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/app/lib/grades/grades_service/src/term.dart b/app/lib/grades/grades_service/src/term.dart
index 783574209..453020ac2 100644
--- a/app/lib/grades/grades_service/src/term.dart
+++ b/app/lib/grades/grades_service/src/term.dart
@@ -592,7 +592,8 @@ class GradeModel extends Equatable {
 /// This is better than just checking for non-negativity in the code because it
 /// makes it impossible to create a negative weight in the first place.
 class NonNegativeWeight extends Weight {
-  NonNegativeWeight.fromWeight(Weight weight) : super.factor(weight.asFactor);
+  factory NonNegativeWeight.fromWeight(Weight weight) =>
+      NonNegativeWeight.factor(weight.asFactor);
   NonNegativeWeight.factor(num factor) : super.factor(factor) {
     if (factor < 0) {
       throw ArgumentError('Weight must be non-negative');