test: add unit tests for BookMarkModel

Author: adityashirsatrao007

test/book_mark_model_test.dart

@@ -0,0 +1,65 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+import 'package:opso/modals/book_mark_model.dart';
+
+void main() {
+  TestWidgetsFlutterBinding.ensureInitialized();
+
+  group('HandleBookmark Tests', () {
+    setUp(() {
+      SharedPreferences.setMockInitialValues({});
+    });
+
+    test('should return empty list when no bookmarks are saved', () async {
+      final bookmarks = await HandleBookmark.loadBookmarks();
+      expect(bookmarks, isEmpty);
+    });
+
+    test('should save and load bookmarks correctly', () async {
+      final bookmarksToSave = [
+        {'title': 'GSSoC', 'screen': 'gssoc_screen'},
+        {'title': 'LFX', 'screen': 'lfx_screen'},
+      ];
+
+      await HandleBookmark.saveBookmarks(bookmarksToSave);
+      final loadedBookmarks = await HandleBookmark.loadBookmarks();
+
+      expect(loadedBookmarks.length, 2);
+      expect(loadedBookmarks[0]['title'], 'GSSoC');
+      expect(loadedBookmarks[1]['title'], 'LFX');
+    });
+
+    test('should add bookmark and prevent duplicates', () async {
+      await HandleBookmark.addBookmark('GSSoC', 'gssoc_screen');
+      
+      var bookmarks = await HandleBookmark.loadBookmarks();
+      expect(bookmarks.length, 1);
+      expect(bookmarks[0]['title'], 'GSSoC');
+
+      // Attempt to add duplicate
+      await HandleBookmark.addBookmark('GSSoC', 'gssoc_screen');
+      bookmarks = await HandleBookmark.loadBookmarks();
+      expect(bookmarks.length, 1); // Should still be 1
+    });
+
+    test('should check if screen is bookmarked correctly', () async {
+      expect(await HandleBookmark.isBookmarked('GSSoC'), isFalse);
+      
+      await HandleBookmark.addBookmark('GSSoC', 'gssoc_screen');
+      expect(await HandleBookmark.isBookmarked('GSSoC'), isTrue);
+    });
+
+    test('should delete bookmark correctly', () async {
+      await HandleBookmark.addBookmark('GSSoC', 'gssoc_screen');
+      await HandleBookmark.addBookmark('LFX', 'lfx_screen');
+      
+      expect(await HandleBookmark.isBookmarked('GSSoC'), isTrue);
+      expect(await HandleBookmark.isBookmarked('LFX'), isTrue);
+
+      await HandleBookmark.deleteBookmark('GSSoC');
+      
+      expect(await HandleBookmark.isBookmarked('GSSoC'), isFalse);
+      expect(await HandleBookmark.isBookmarked('LFX'), isTrue);
+    });
+  });
+}