Fixes for aioca 1.8.* and general CI cleanup issue

aioca 1.8 changed its atexit handling to work better with other EPICS
libraries. Note that cothread isn't quite so nice so there still needs
to be some accomodation for that.

Sometimes the CI would be unable to delete its temporary dir used for
test results, thus failing the build.

Author: AlexanderWells-diamond

.github/workflows/code.yml

@@ -95,7 +95,11 @@ jobs:
         env:
           CIBW_BUILD: ${{ matrix.python }}*64
           CIBW_TEST_EXTRAS: dev
-          CIBW_TEST_COMMAND: pytest {project}/tests --cov-report xml:${{ matrix.cov_file }} --junit-xml=${{ matrix.results_file }}
+          # Added a sleep command afterwards to let all cleanup finish; sometimes
+          # cibuildwheel reports it cannot clean up the temp dir used for testing,
+          # and fails the build. Sleeping seems to give pytest enough time to
+          # fully clean up.
+          CIBW_TEST_COMMAND: pytest {project}/tests --cov-report xml:${{ matrix.cov_file }} --junit-xml=${{ matrix.results_file }} && sleep 2
           # Run with faulthandler and -s in the hope we get a stack trace on seg fault on windows...
           CIBW_TEST_COMMAND_WINDOWS: python -X faulthandler -m pytest -s {project}/tests --cov-report xml:${{ matrix.cov_file }} --junit-xml=${{ matrix.results_file }}
           # Disable auditwheel as it isn't compatible with setuptools_dso approach

tests/conftest.py

@@ -6,9 +6,20 @@
 import string
 import subprocess
 import sys
+from packaging.version import Version
 from typing import Any
 import pytest
 
+# It is necessary to ensure we always import cothread.catools before aioca as
+# doing this import will cause an EPICS context to be created, and it will also
+# register an atexit function to delete it.
+# If we were to import aioca first it would create an EPICS context, note it has
+# created it, then try to delete it in its own atexit function which will
+# collide with cothread's attempts to do the same (despite the fact in this
+# configuration cothread did not create the context)
+if os.name != "nt":
+    import cothread.catools
+
 from softioc import builder
 from softioc.builder import ClearRecords, SetDeviceName, GetRecordNames
 
@@ -73,12 +84,17 @@ def cothread_ioc():
 
 
 def aioca_cleanup():
-    from aioca import purge_channel_caches, _catools
+    from aioca import purge_channel_caches, _catools, __version__
     # Unregister the aioca atexit handler as it conflicts with the one installed
     # by cothread. If we don't do this we get a seg fault. This is not a problem
     # in production as we won't mix aioca and cothread, but we do mix them in
     # the tests so need to do this.
-    atexit.unregister(_catools._Context._destroy_context)
+    # In aioca 1.8 the atexit function was changed to no longer cause this
+    # issue, when coupled with ensuring cothread is always imported first.
+    if Version(__version__) < Version("1.8"):
+        unregister_func = _catools._Context._destroy_context
+        atexit.unregister(unregister_func)
+
     # purge the channels before the event loop goes
     purge_channel_caches()