(#1252) Fix logging unit test failure

tests/conftest.py

@@ -1,3 +1,4 @@
+import logging
 import sys
 import threading
 from functools import partial
@@ -81,7 +82,16 @@ def create_dummy_scan_spec(x_steps, y_steps, z_steps):
     return [spec.consume().midpoints for spec in specs]
 
 
-def _destroy_loggers(loggers):
+def _reset_loggers(loggers):
+    """Clear all handlers and tear down the logging hierarchy, leave logger references intact."""
+    clear_log_handlers(loggers)
+    for logger in loggers:
+        if logger.name != "Hyperion":
+            # Hyperion parent is configured on module import, do not remove
+            logger.parent = logging.getLogger()
+
+
+def clear_log_handlers(loggers):
     for logger in loggers:
         for handler in logger.handlers:
             handler.close()
@@ -115,12 +125,15 @@ def pytest_runtest_setup(item):
             )
     else:
         print("Skipping log setup for log test - deleting existing handlers")
-        _destroy_loggers([*ALL_LOGGERS, dodal_logger])
+        _reset_loggers([*ALL_LOGGERS, dodal_logger])
 
 
-def pytest_runtest_teardown():
+def pytest_runtest_teardown(item):
     if "dodal.beamlines.beamline_utils" in sys.modules:
         sys.modules["dodal.beamlines.beamline_utils"].clear_devices()
+    markers = [m.name for m in item.own_markers]
+    if item.config.getoption("logging") and "skip_log_setup" in markers:
+        _reset_loggers([*ALL_LOGGERS, dodal_logger])
 
 
 @pytest.fixture

tests/unit_tests/hyperion/test_log/conftest.py

@@ -2,12 +2,12 @@
 
 from hyperion.log import ALL_LOGGERS
 
-from ....conftest import _destroy_loggers
+from ....conftest import _reset_loggers
 
 
 def pytest_runtest_setup():
-    _destroy_loggers([*ALL_LOGGERS, LOGGER])
+    _reset_loggers([*ALL_LOGGERS, LOGGER])
 
 
 def pytest_runtest_teardown():
-    _destroy_loggers([*ALL_LOGGERS, LOGGER])
+    _reset_loggers([*ALL_LOGGERS, LOGGER])

tests/unit_tests/hyperion/test_log/test_log.py

@@ -14,12 +14,12 @@
     LogUidTaggingCallback,
 )
 
-from .conftest import _destroy_loggers
+from ....conftest import clear_log_handlers
 
 
 @pytest.fixture(scope="function")
 def clear_and_mock_loggers():
-    _destroy_loggers([*log.ALL_LOGGERS, dodal_logger])
+    clear_log_handlers([*log.ALL_LOGGERS, dodal_logger])
     mock_open_with_tell = MagicMock()
     mock_open_with_tell.tell.return_value = 0
     with (
@@ -30,7 +30,7 @@ def clear_and_mock_loggers():
         graylog_emit.reset_mock()
         filehandler_emit.reset_mock()
         yield filehandler_emit, graylog_emit
-    _destroy_loggers([*log.ALL_LOGGERS, dodal_logger])
+    clear_log_handlers([*log.ALL_LOGGERS, dodal_logger])
 
 
 @pytest.mark.skip_log_setup