The api_test::test_get_message_processor() test fails when the first processor plugin returned by get_message_processors() is unconfigured by default.

The failure message is:

1) core_message_api_testcase::test_get_message_processor
Trying to get property of non-object

/var/lib/jenkins/workspace/s-build/moodle/message/tests/api_test.php:902
/var/lib/jenkins/workspace/s-build/moodle/lib/phpunit/classes/advanced_testcase.php:80

To re-run:
vendor/bin/phpunit core_message_api_testcase message/tests/api_test.php

The easiest way to replicate this is:

• delete the /message/output/popup directory
• run vendor/bin/phpunit --filter=test_get_user_notification_preferences core_message_api_testcase message/tests/api_test.php

(The replication steps work by making the jabber processor the first returned by get_message_processors(). You can confirm the test passes with missing processors by deleting the jabber one too.)

We're seeing this manifested when running unit tests with a third-party plugin whose name begins with S (they're returned in reverse alphabetical order).