SIENTIAPDE-1975: Sonar fixes in the NATS consumer tests

- One call per pytest.raises block (S5778): build the guarded start()
  before the block and nest the patch outside it.
- The NATS callbacks stay async on purpose: nats-py rejects callbacks
  that are not coroutine functions. Comment it and assert it in the
  callback test, so nobody drops the async keyword to please S7503.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

ingestor/adapters/nats_consumer.py

@@ -94,6 +94,8 @@ class NatsWriteConsumer:
                 f'{traceback.format_exc()}'
             )
 
+    # These stay async with nothing to await: nats-py rejects callbacks that are not
+    # coroutine functions (InvalidCallbackTypeError on connect).
     async def _on_error(self, e: Exception) -> None:
         self.logger.warning(f'NATS error: {type(e).__name__} {e}')
 

tests/unit/adapters/test_nats_consumer.py

@@ -1,4 +1,5 @@
 import asyncio
+import inspect
 import json
 from unittest.mock import AsyncMock, MagicMock, patch
 
@@ -76,9 +77,12 @@ async def test_start_gives_up_after_the_connect_timeout():
     """start() runs on the main loop: an unreachable NATS must not block it."""
     consumer = make_consumer(connect_timeout_s=0.1)
     nc = _fake_nc(connect=AsyncMock(side_effect=_hang))
+    # Outer guard: fails the test instead of hanging it if start() ignores its timeout.
+    start = asyncio.wait_for(consumer.start(), timeout=5)
 
-    with patch(CLIENT, return_value=nc), pytest.raises(TimeoutError):
+    with patch(CLIENT, return_value=nc):
-        await asyncio.wait_for(consumer.start(), timeout=5)
+        with pytest.raises(TimeoutError):
+            await start
 
     nc.close.assert_awaited_once()
     assert consumer.closed is True
@@ -115,6 +119,9 @@ async def test_connection_events_are_logged_in_one_line():
     with patch(CLIENT, return_value=nc):
         await consumer.start()
     callbacks = nc.connect.await_args.kwargs
+    # nats-py raises InvalidCallbackTypeError on connect for a non-coroutine callback.
+    for name in ('error_cb', 'disconnected_cb', 'reconnected_cb'):
+        assert inspect.iscoroutinefunction(callbacks[name]), name
 
     await callbacks['error_cb'](OSError('connection refused'))
     await callbacks['disconnected_cb']()