This check does not really makes sense as a group was never needed
for a test to be executed on Travis. The testsuites that always have been
used on Travis automatically execute all tests within the PHPUnit/Unit
Integration and System folder. A group was never needed. Maybe some
developers used groups to execute tests but then always only a part of
the tests was executed as a test does not necessarily has the "correct"
group. Removing this check is also important for plugin developers who
write tests for their plugin as we cannot expect that they set a group
as it is usually not needed in any other project. If plugin developers
do not set a group and we run our automated tests no test
would be executed because of this unneeded check.
Does it mean
<a class='mention' href='https://github.com/group'>@group</a> Core is not needed on tests in Core?
Exactly. It is nice to have but not really mandatory and not even so useful. At some point we could maybe even add groups "dynamically" as we now core tests are always in
tests/PHPUnit/ and plugin tests are always in