Log but don't raise when publish fails

Closes #4

Author: thatbudakguy

mqlog/__init__.py

@@ -39,6 +39,7 @@ def __init__(
         self.capacity = capacity
         self.buffer = []
         self.will_flush = asyncio.Event()
+        self._logger = logging.getLogger("mqlog")
 
     async def run(self):
         """
@@ -69,8 +70,9 @@ def format(self, record):
     # Named with an underscore to avoid conflict with logging.Handler.flush
     async def _flush(self):
         if self.buffer:
-            msg = ""
-            while self.buffer:
-                msg += self.buffer.pop(0) + "\n"
-            await self.client.publish(self.topic, msg.strip(), qos=self.qos)
-        self.will_flush.clear()
+            try:
+                msg = "\n".join([line for line in self.buffer])
+                await self.client.publish(self.topic, msg, qos=self.qos)
+                self.will_flush.clear()
+            except Exception as e:
+                self._logger.error("Failed to publish logs", exc_info=e)

tests/test_handler.py

@@ -4,17 +4,14 @@
 from unittest import TestCase, skipIf
 
 from mqlog import MqttHandler
+from tests.utils import AsyncMock, Mock
 
 
 class FakeClient:
     """A fake MQTT client for testing purposes."""
 
     def __init__(self):
-        self.calls = []
-
-    # Store the call like a mock so we can check it later
-    async def publish(self, topic, payload, qos=0):
-        self.calls.append((topic, payload, qos))
+        self.publish = AsyncMock()
 
 
 class TestMqttHandler(TestCase):
@@ -50,6 +47,23 @@ def test_flush_full_buffer(self):
             self.logger.info(f"Test message {i}")
         self.assertTrue(self.handler.will_flush.is_set())
 
+    def test_flush_fail(self):
+        """Flushing should log an error if publish fails"""
+        self.handler._logger.error = Mock()
+        self.client.publish = AsyncMock(side_effect=Exception("Publish failed"))
+        asyncio.create_task(self.handler.run())
+
+        async def do_test(logger):
+            await asyncio.sleep(0.1)  # Allow handler to start
+            logger.error("Test message")    # should trigger flush
+        
+        asyncio.run(do_test(self.logger))
+        self.assertTrue(self.handler.will_flush.is_set())
+        self.handler._logger.error.assert_called_with(
+            "Failed to publish log message: Publish failed"
+        )
+
+
     @skipIf(os.getenv("CI"), "Hangs in CI")
     def test_publish(self):
         """Flushing should publish messages to MQTT topic"""