SIENTIAPDE-1205

Enhance unit tests for async shutdown and improve assertions

- Updated `test_app.py` to verify multiple calls to `asyncio_sleep` and ensure proper handling of sleep intervals.
- Added new tests in `test_ingestor.py` and `test_opc_manager.py` to validate shutdown behavior and error handling for async operations.
- Improved assertions in existing tests to enhance reliability and clarity of test outcomes.

tests/unit/managers/test_opc_manager.py

@@ -1,6 +1,6 @@
 import json
 from datetime import datetime
-from unittest.mock import AsyncMock, MagicMock, patch
+from unittest.mock import AsyncMock, MagicMock, call, patch
 from pytest import fixture, mark
 from asyncua.crypto.security_policies import SecurityPolicyBasic256
 import pytest
@@ -80,6 +80,25 @@ def test___str__(opc_manager):
     )
 
 
+@mark.asyncio
+async def test_shutdown_success(opc_manager):
+    opc_manager.disconnect = AsyncMock()
+
+    await opc_manager.shutdown()
+
+    opc_manager.disconnect.assert_called_once()
+
+
+@mark.asyncio
+async def test_shutdown_error(opc_manager):
+    opc_manager.disconnect = AsyncMock(side_effect=Exception("Test error"))
+
+    await opc_manager.shutdown()
+
+    opc_manager.logger.error.assert_called_once_with(
+        "Error during cleanup: Test error")
+
+
 @mark.asyncio
 async def test_set_security_success(opc_manager):
     await opc_manager.set_security()
@@ -326,6 +345,18 @@ async def test_disconnect_success(opc_manager_subscribed):
     assert opc_manager_subscribed.client is None
 
 
+@mark.asyncio
+async def test_disconnect_no_client(opc_manager_subscribed):
+    opc_manager_subscribed.client = None
+    assert await opc_manager_subscribed.disconnect() is None
+
+    opc_manager_subscribed.logger.warning.assert_has_calls(
+        [
+            call("Client already disconnected."),
+        ]
+    )
+
+
 @mark.asyncio
 async def test_disconnect_error_unsubscribe(opc_manager_subscribed):
     opc_manager_subscribed.client = MagicMock(