tests: Trigger Pytest failure when an unraisable exception occurs (#4738)

Set Pytest command-line argument to return non-zero exit code when an unraisable exception is encountered.

Closes #4723.

Author: alexander-alderman-webb

scripts/populate_tox/tox.jinja

@@ -429,7 +429,7 @@ commands =
     ; Running `pytest` as an executable suffers from an import error
     ; when loading tests in scenarios. In particular, django fails to
     ; load the settings from the test module.
-    python -m pytest {env:TESTPATH} -o junit_suite_name={envname} {posargs}
+    python -m pytest -W error::pytest.PytestUnraisableExceptionWarning {env:TESTPATH} -o junit_suite_name={envname} {posargs}
 
 [testenv:linters]
 commands =

tox.ini

@@ -10,7 +10,7 @@
 # The file (and all resulting CI YAMLs) then need to be regenerated via
 # "scripts/generate-test-files.sh".
 #
-# Last generated: 2025-09-02T10:59:55.249513+00:00
+# Last generated: 2025-09-02T12:34:09.591543+00:00
 
 [tox]
 requires =
@@ -909,7 +909,7 @@ commands =
     ; Running `pytest` as an executable suffers from an import error
     ; when loading tests in scenarios. In particular, django fails to
     ; load the settings from the test module.
-    python -m pytest {env:TESTPATH} -o junit_suite_name={envname} {posargs}
+    python -m pytest -W error::pytest.PytestUnraisableExceptionWarning {env:TESTPATH} -o junit_suite_name={envname} {posargs}
 
 [testenv:linters]
 commands =