Add unit tests for chat logic

.gitignore

@@ -1,2 +1,3 @@
 /.access/
 /logs/
+__pycache__/

tests/test_chat.py

@@ -0,0 +1,41 @@
+import unittest
+from unittest.mock import patch, MagicMock
+import chat
+
+class TestChat(unittest.TestCase):
+    @patch('chat.requests.post')
+    def test_send_payload_trims_context(self, mock_post):
+        chat.config = {
+            'api_key': 'token',
+            'url': 'http://example.com',
+            'model': 'gpt',
+            'role': 'user',
+            'temperature': '0',
+            'context_length': 2,
+        }
+        chat.context = [
+            {'role': 'user', 'content': 'u1'},
+            {'role': 'assistant', 'content': 'a1'},
+            {'role': 'user', 'content': 'u2'},
+            {'role': 'assistant', 'content': 'a2'},
+        ]
+
+        mock_post.return_value.json.return_value = {}
+
+        chat.send_payload('u3')
+
+        self.assertEqual(len(chat.context), 3)
+        self.assertEqual(chat.context[0]['content'], 'u2')
+        self.assertEqual(chat.context[1]['content'], 'a2')
+        self.assertEqual(chat.context[2]['content'], 'u3')
+
+    def test_process_response_appends(self):
+        chat.config = {}
+        chat.context = []
+        response = {'choices': [{'message': {'role': 'assistant', 'content': 'reply'}}]}
+        with patch('builtins.print'):
+            chat.process_response(response)
+        self.assertEqual(chat.context[-1], {'role': 'assistant', 'content': 'reply'})
+
+if __name__ == '__main__':
+    unittest.main()