chat: added 'update_messages()' function and test

tests/test_chat.py

@@ -440,3 +440,31 @@ class TestChatDB(unittest.TestCase):
         cache_dir_files = self.message_list(self.cache_path)
         self.assertEqual(len(cache_dir_files), 1)
         self.assertIn(pathlib.Path(self.cache_path.name, '123456.txt'), cache_dir_files)
+
+    def test_chat_db_update_messages(self) -> None:
+        # create a new ChatDB instance
+        chat_db = ChatDB.from_dir(pathlib.Path(self.cache_path.name),
+                                  pathlib.Path(self.db_path.name))
+
+        db_dir_files = self.message_list(self.db_path)
+        self.assertEqual(len(db_dir_files), 4)
+        cache_dir_files = self.message_list(self.cache_path)
+        self.assertEqual(len(cache_dir_files), 0)
+
+        message = chat_db.messages[0]
+        message.answer = Answer("New answer")
+        # update message without writing
+        chat_db.update_messages([message], write=False)
+        self.assertEqual(chat_db.messages[0].answer, Answer("New answer"))
+        # re-read the message and check for old content
+        chat_db.read_db()
+        self.assertEqual(chat_db.messages[0].answer, Answer("Answer 1"))
+        # now check with writing (message should be overwritten)
+        chat_db.update_messages([message], write=True)
+        chat_db.read_db()
+        self.assertEqual(chat_db.messages[0].answer, Answer("New answer"))
+        # test without file_path -> expect error
+        message1 = Message(question=Question("Question 1"),
+                           answer=Answer("Answer 1"))
+        with self.assertRaises(ChatError):
+            chat_db.update_messages([message1])