Splitting this off from 📌 [meta] Convert some tests to Build tests Active after Spokje queried why we are testing drush. I also learned from Gábor Hojtsy about the core ideas issue ✨ Add drush/drush to Drupal Composer project templates Active .
So, moving the exiting work to this issue where we can first decide that this is something we want to test in core.
For background about adding tests with Drush there are relevant comments in the original issue.
#3082230-14: [meta] Convert some tests to Build tests →
Point 3. Mile23 questions if Drush is an official way to update, so should we test with it.
#3082230-15: [meta] Convert some tests to Build tests →
heddn added several versions of Drush because of 'strong complaints' last time with Phar and Drush testing.
#3082230-21: [meta] Convert some tests to Build tests →
alexpott states that Drush test would have to be allowed to fail.
Decide testing updates with Drush should be added to core.