add permission test

Author: fadi-george

test/permission_test.dart

@@ -0,0 +1,64 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:onesignal_flutter/src/permission.dart';
+
+void main() {
+  TestWidgetsFlutterBinding.ensureInitialized();
+
+  group('OSPermissionState', () {
+    group('constructor', () {
+      test('initializes with permission true when provided in json', () {
+        final json = {'permission': true};
+        final state = OSPermissionState(json);
+
+        expect(state.permission, true);
+      });
+
+      test('defaults to false when permission key is missing', () {
+        final json = <String, dynamic>{};
+        final state = OSPermissionState(json);
+
+        expect(state.permission, false);
+      });
+    });
+
+    group('jsonRepresentation', () {
+      test('returns json string with permission true', () {
+        final json = {'permission': true};
+        final state = OSPermissionState(json);
+        final jsonString = state.jsonRepresentation();
+
+        expect(jsonString, contains('"permission": true'));
+      });
+
+      test('returns properly formatted json string', () {
+        final json = {'permission': true};
+        final state = OSPermissionState(json);
+        final jsonString = state.jsonRepresentation();
+
+        expect(jsonString, contains('"permission": true'));
+      });
+    });
+
+    group('permission field', () {
+      test('can be modified after construction', () {
+        final json = {'permission': false};
+        final state = OSPermissionState(json);
+
+        expect(state.permission, false);
+
+        state.permission = true;
+        expect(state.permission, true);
+      });
+
+      test('reflects changes in jsonRepresentation', () {
+        final json = {'permission': false};
+        final state = OSPermissionState(json);
+
+        state.permission = true;
+        final jsonString = state.jsonRepresentation();
+
+        expect(jsonString, contains('"permission": true'));
+      });
+    });
+  });
+}