diff --git a/test/widgets/app_theme_test.dart b/test/widgets/app_theme_test.dart
new file mode 100644
index 00000000..da7a852f
--- /dev/null
+++ b/test/widgets/app_theme_test.dart
@@ -0,0 +1,40 @@
+import 'package:flutter/cupertino.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:gsettings/gsettings.dart';
+import 'package:mockito/annotations.dart';
+import 'package:settings/view/app_theme.dart';
+import 'app_theme_test.mocks.dart';
+import 'package:mockito/mockito.dart';
+
+@GenerateMocks([GSettings])
+void main() {
+  test(
+    'App Theme Dark Mode Test',
+    () {
+      GSettings settings = MockGSettings();
+      AppTheme theme = AppTheme(settings);
+
+      when(settings.setValue('gtk-theme', 'Yaru-dark')).thenAnswer(
+        (realInvocation) => true,
+      );
+
+      theme.apply(Brightness.dark);
+      verify(settings.setValue('gtk-theme', 'Yaru-dark')).called(1);
+    },
+  );
+
+  test(
+    'App Theme Light Mode Test',
+    () {
+      GSettings settings = MockGSettings();
+      AppTheme theme = AppTheme(settings);
+
+      when(settings.setValue('gtk-theme', 'Yaru')).thenAnswer(
+        (realInvocation) => true,
+      );
+
+      theme.apply(Brightness.light);
+      verify(settings.setValue('gtk-theme', 'Yaru')).called(1);
+    },
+  );
+}
diff --git a/test/widgets/app_theme_test.mocks.dart b/test/widgets/app_theme_test.mocks.dart
new file mode 100644
index 00000000..30ad667d
--- /dev/null
+++ b/test/widgets/app_theme_test.mocks.dart
@@ -0,0 +1,152 @@
+// Mocks generated by Mockito 5.0.16 from annotations
+// in settings/test/widgets/app_theme_test.dart.
+// Do not manually edit this file.
+
+import 'dart:ffi' as _i1;
+
+import 'package:gsettings/src/bindings.dart' as _i5;
+import 'package:gsettings/src/settings.dart' as _i3;
+import 'package:mockito/mockito.dart' as _i2;
+import 'package:more/more.dart' as _i4;
+
+// ignore_for_file: avoid_redundant_argument_values
+// ignore_for_file: avoid_setters_without_getters
+// ignore_for_file: comment_references
+// ignore_for_file: implementation_imports
+// ignore_for_file: invalid_use_of_visible_for_testing_member
+// ignore_for_file: prefer_const_constructors
+// ignore_for_file: unnecessary_parenthesis
+// ignore_for_file: camel_case_types
+
+
+class _FakeGSettings_1 extends _i2.Fake implements _i3.GSettings {}
+
+class _FakeTuple_2 extends _i2.Fake implements _i4.Tuple {}
+
+/// A class which mocks [GSettings].
+///
+/// See the documentation for Mockito's code generation for more information.
+// ignore: must_be_immutable
+class MockGSettings extends _i2.Mock implements _i3.GSettings {
+  MockGSettings() {
+    _i2.throwOnMissingStub(this);
+  }
+
+  @override
+  List<Object> get props =>
+      (super.noSuchMethod(Invocation.getter(#props), returnValue: <Object>[])
+          as List<Object>);
+  @override
+  String get schemaId =>
+      (super.noSuchMethod(Invocation.getter(#schemaId), returnValue: '')
+          as String);
+  @override
+  String get path =>
+      (super.noSuchMethod(Invocation.getter(#path), returnValue: '') as String);
+
+  @override
+  void sync() => super.noSuchMethod(Invocation.method(#sync, []),
+      returnValueForMissingStub: null);
+  @override
+  void dispose() => super.noSuchMethod(Invocation.method(#dispose, []),
+      returnValueForMissingStub: null);
+  @override
+  Object? value(String? key) =>
+      (super.noSuchMethod(Invocation.method(#value, [key])) as Object?);
+  @override
+  bool setValue(String? key, Object? value) =>
+      (super.noSuchMethod(Invocation.method(#setValue, [key, value]),
+          returnValue: false) as bool);
+  @override
+  bool isWritable(String? key) =>
+      (super.noSuchMethod(Invocation.method(#isWritable, [key]),
+          returnValue: false) as bool);
+  @override
+  void delay() => super.noSuchMethod(Invocation.method(#delay, []),
+      returnValueForMissingStub: null);
+  @override
+  void apply() => super.noSuchMethod(Invocation.method(#apply, []),
+      returnValueForMissingStub: null);
+  @override
+  void revert() => super.noSuchMethod(Invocation.method(#revert, []),
+      returnValueForMissingStub: null);
+  @override
+  bool hasUnapplied() =>
+      (super.noSuchMethod(Invocation.method(#hasUnapplied, []),
+          returnValue: false) as bool);
+  @override
+  _i3.GSettings child(String? name) =>
+      (super.noSuchMethod(Invocation.method(#child, [name]),
+          returnValue: _FakeGSettings_1()) as _i3.GSettings);
+  @override
+  void resetValue(String? key) =>
+      super.noSuchMethod(Invocation.method(#resetValue, [key]),
+          returnValueForMissingStub: null);
+  @override
+  Object? userValue(String? key) =>
+      (super.noSuchMethod(Invocation.method(#userValue, [key])) as Object?);
+  @override
+  Object? defaultValue(String? key) =>
+      (super.noSuchMethod(Invocation.method(#defaultValue, [key])) as Object?);
+  @override
+  List<String> children() =>
+      (super.noSuchMethod(Invocation.method(#children, []),
+          returnValue: <String>[]) as List<String>);
+  @override
+  bool boolValue(String? key) =>
+      (super.noSuchMethod(Invocation.method(#boolValue, [key]),
+          returnValue: false) as bool);
+  @override
+  int intValue(String? key) =>
+      (super.noSuchMethod(Invocation.method(#intValue, [key]), returnValue: 0)
+          as int);
+  @override
+  double doubleValue(String? key) =>
+      (super.noSuchMethod(Invocation.method(#doubleValue, [key]),
+          returnValue: 0.0) as double);
+  @override
+  String stringValue(String? key) => (super
+          .noSuchMethod(Invocation.method(#stringValue, [key]), returnValue: '')
+      as String);
+  @override
+  Object? maybeValue(String? key) =>
+      (super.noSuchMethod(Invocation.method(#maybeValue, [key])) as Object?);
+  @override
+  Map<Object, Object?> dictValue(String? key) =>
+      (super.noSuchMethod(Invocation.method(#dictValue, [key]),
+          returnValue: <Object, Object?>{}) as Map<Object, Object?>);
+  @override
+  List<Object?> arrayValue(String? key) =>
+      (super.noSuchMethod(Invocation.method(#arrayValue, [key]),
+          returnValue: <Object?>[]) as List<Object?>);
+  @override
+  List<int?> byteArrayValue(String? key) =>
+      (super.noSuchMethod(Invocation.method(#byteArrayValue, [key]),
+          returnValue: <int?>[]) as List<int?>);
+  @override
+  List<String?> stringArrayValue(String? key) =>
+      (super.noSuchMethod(Invocation.method(#stringArrayValue, [key]),
+          returnValue: <String?>[]) as List<String?>);
+  @override
+  _i4.Tuple tupleValue(String? key) =>
+      (super.noSuchMethod(Invocation.method(#tupleValue, [key]),
+          returnValue: _FakeTuple_2()) as _i4.Tuple);
+  @override
+  int enumValue(String? key) =>
+      (super.noSuchMethod(Invocation.method(#enumValue, [key]), returnValue: 0)
+          as int);
+  @override
+  bool setEnumValue(String? key, int? value) =>
+      (super.noSuchMethod(Invocation.method(#setEnumValue, [key, value]),
+          returnValue: false) as bool);
+  @override
+  int flagsValue(String? key) =>
+      (super.noSuchMethod(Invocation.method(#flagsValue, [key]), returnValue: 0)
+          as int);
+  @override
+  bool setFlagsValue(String? key, int? value) =>
+      (super.noSuchMethod(Invocation.method(#setFlagsValue, [key, value]),
+          returnValue: false) as bool);
+  @override
+  String toString() => super.toString();
+}