test: add unit tests for HyperledgerProjectModal

Comprehensive unit tests for HyperledgerProjectModal covering:
- Constructor field initialization
- fromJson() with list and string mentor values
- fromJson() integer-to-string year conversion
- toJson() serialization
- toString() output
- Edge case: empty mentors list

Author: adityashirsatrao007

test/hyperledger_modal_test.dart

@@ -0,0 +1,80 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:opso/modals/hyperledger_modal.dart';
+
+void main() {
+  group('HyperledgerProjectModal', () {
+    final tModal = HyperledgerProjectModal(
+      name: 'TestProject',
+      wiki: 'https://wiki.hyperledger.org/test',
+      mentors: ['Alice', 'Bob'],
+      year: '2023',
+    );
+
+    test('constructor sets all fields correctly', () {
+      expect(tModal.name, 'TestProject');
+      expect(tModal.wiki, 'https://wiki.hyperledger.org/test');
+      expect(tModal.mentors, ['Alice', 'Bob']);
+      expect(tModal.year, '2023');
+    });
+
+    test('fromJson with list mentors', () {
+      final json = {
+        'title': 'ListMentorProject',
+        'link': 'https://wiki.hyperledger.org/list',
+        'mentors': ['Mentor1', 'Mentor2'],
+        'year': 2023,
+      };
+      final modal = HyperledgerProjectModal.fromJson(json);
+      expect(modal.name, 'ListMentorProject');
+      expect(modal.mentors, ['Mentor1', 'Mentor2']);
+      expect(modal.year, '2023');
+    });
+
+    test('fromJson with string mentor', () {
+      final json = {
+        'title': 'SingleMentorProject',
+        'link': 'https://wiki.hyperledger.org/single',
+        'mentors': 'SingleMentor',
+        'year': 2022,
+      };
+      final modal = HyperledgerProjectModal.fromJson(json);
+      expect(modal.mentors, ['SingleMentor']);
+    });
+
+    test('fromJson converts year int to string', () {
+      final json = {
+        'title': 'YearTest',
+        'link': 'url',
+        'mentors': <String>[],
+        'year': 2024,
+      };
+      final modal = HyperledgerProjectModal.fromJson(json);
+      expect(modal.year, '2024');
+    });
+
+    test('toJson returns correct map', () {
+      final map = tModal.toJson();
+      expect(map['title'], 'TestProject');
+      expect(map['link'], 'https://wiki.hyperledger.org/test');
+      expect(map['mentors'], ['Alice', 'Bob']);
+      expect(map['year'], '2023');
+    });
+
+    test('toString contains key fields', () {
+      final str = tModal.toString();
+      expect(str, contains('TestProject'));
+      expect(str, contains('Alice'));
+      expect(str, contains('2023'));
+    });
+
+    test('supports empty mentors list', () {
+      final modal = HyperledgerProjectModal(
+        name: 'NoMentor',
+        wiki: 'url',
+        mentors: [],
+        year: '2023',
+      );
+      expect(modal.mentors, isEmpty);
+    });
+  });
+}