Headline - used to work in 4.1, but doesn't in 4.4
I followed the instructions for writing tests here - https://moodledev.io/docs/4.4/apis/subsystems/external/testing
In 4.1 it worked. The external class (get_fruit in the docs) was found. In (https://docs.moodle.org/dev/Writing_PHPUnit_tests) it says "grand summary = 100% the same rules that are applied to **/classes directories", so all that adds up.
However, in 4.4, it is no longer found. Even explicitly specifying the full class name (local_myplugin\external\get_fruit) does not find the class - so something seems to have changed.
The actual error is...
Error: Class "local_myplugin\external\my_external_class" not found
...that class definitely exists, and (as mentioned) it all worked in 4.1.
Any ideas?