Refactor RendezqueueClient callbacks to be optional and use logging

- Change `on_data` and `on_error` parameters in `RendezqueueClient.__init__` to be optional (default `None`).
- Change `on_error` default behavior from `print(e)` to `logging.error`.
- Add type hints to `RendezqueueClient.__init__`.
- Add test case `test_defaults` in `test/client_test.py` to verify safe instantiation without callbacks.
- Ensure backwards compatibility (explicitly passed callbacks still work).
- Ensure thread safety and no crashes when callbacks are `None`.

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

Author: gendeux

src/rendezqueue/client.py

@@ -1,19 +1,23 @@
 import base64
 import json
+import logging
 import random
 import string
 import threading
 import time
 import urllib.request
 import urllib.error
+from typing import Callable, Optional, List
+
+logger = logging.getLogger(__name__)
 
 class RendezqueueClient:
-    def __init__(self, url, key, hue, on_data, on_error=None, poll_interval_ms=2000):
+    def __init__(self, url: str, key: str, hue: str, on_data: Optional[Callable[[List[bytes]], None]] = None, on_error: Optional[Callable[[Exception], None]] = None, poll_interval_ms: int = 2000):
         self.url = url
         self.key = key
         self.hue = hue
         self.on_data = on_data
-        self.on_error = on_error or (lambda e: print(e))
+        self.on_error = on_error or (lambda e: logger.error(f"Rendezqueue error: {e}"))
         self.poll_interval_ms = poll_interval_ms
 
         self.sid_counter = 1

test/client_test.py

@@ -114,5 +114,35 @@ def test_decode_padding(self):
         decoded = self.client._decode_response(msg)
         self.assertEqual(decoded['values'][0], b"test padding")
 
+    @patch("urllib.request.urlopen")
+    def test_defaults(self, mock_urlopen):
+        # Initialize client without callbacks
+        client = RendezqueueClient(
+            url=self.url,
+            key=self.key,
+            hue=self.hue
+        )
+        self.assertIsNone(client.on_data)
+        self.assertIsNotNone(client.on_error) # Should be default logger lambda
+
+        # Simulate receiving data
+        resp_values = [base64.b64encode(b"response").decode('ascii')]
+        resp_data = {
+            "offset": 1,
+            "values": resp_values,
+            "b64": 1
+        }
+        mock_resp = MagicMock()
+        mock_resp.status = 200
+        mock_resp.read.return_value = json.dumps(resp_data).encode('utf-8')
+        mock_resp.__enter__.return_value = mock_resp
+        mock_urlopen.return_value = mock_resp
+
+        # Trigger poll - should not crash
+        try:
+            client._poll()
+        except Exception as e:
+            self.fail(f"_poll raised exception unexpectedly: {e}")
+
 if __name__ == "__main__":
     unittest.main()