From ef1efc9310fca54d0cb92e5f096e619f91634271 Mon Sep 17 00:00:00 2001
From: dab246 <tdvu@linagora.com>
Date: Tue, 6 Jan 2026 01:12:48 +0700
Subject: [PATCH] TF-4195 Add unit test for `addKeyword` in
 MapKeywordsExtension

---
 .../map_keywords_extension_test.dart          | 65 +++++++++++++++++++
 1 file changed, 65 insertions(+)

diff --git a/test/features/thread/presentation/extensions/map_keywords_extension_test.dart b/test/features/thread/presentation/extensions/map_keywords_extension_test.dart
index 12844d482..80e9a9f7d 100644
--- a/test/features/thread/presentation/extensions/map_keywords_extension_test.dart
+++ b/test/features/thread/presentation/extensions/map_keywords_extension_test.dart
@@ -106,4 +106,69 @@ void main() {
       expect(map.containsKey(keyword), true); // original not mutated
     });
   });
+
+  group('MapKeywordsExtension - addKeyword()', () {
+    test('adds keyword to empty map', () {
+      final map = <KeyWordIdentifier, bool>{};
+      final keyword = KeyWordIdentifier('\$seen');
+
+      map.addKeyword(keyword);
+
+      expect(map.length, 1);
+      expect(map[keyword], true);
+    });
+
+    test('adds keyword to non-empty map', () {
+      final map = {
+        KeyWordIdentifier('\$flagged'): true,
+      };
+      final keyword = KeyWordIdentifier('\$seen');
+
+      map.addKeyword(keyword);
+
+      expect(map.length, 2);
+      expect(map[keyword], true);
+    });
+
+    test('overwrites existing keyword value to true', () {
+      final keyword = KeyWordIdentifier('\$seen');
+
+      final map = {
+        keyword: false,
+      };
+
+      map.addKeyword(keyword);
+
+      expect(map.length, 1);
+      expect(map[keyword], true);
+    });
+
+    test('does not throw when map is null', () {
+      Map<KeyWordIdentifier, bool>? map;
+      final keyword = KeyWordIdentifier('\$seen');
+
+      expect(() => map.addKeyword(keyword), returnsNormally);
+    });
+
+    test('calling addKeyword on null map has no side effects', () {
+      Map<KeyWordIdentifier, bool>? map;
+      final keyword = KeyWordIdentifier('\$seen');
+
+      map.addKeyword(keyword);
+
+      expect(map, isNull);
+    });
+
+    test('mutates the same map instance', () {
+      final map = <KeyWordIdentifier, bool>{};
+      final keyword = KeyWordIdentifier('\$seen');
+
+      final originalIdentity = identityHashCode(map);
+
+      map.addKeyword(keyword);
+
+      expect(identityHashCode(map), originalIdentity);
+      expect(map[keyword], true);
+    });
+  });
 }