MINOR: follow-up test for create topic acl (KIP-277)

[edoardocomar]

Check handling of a Metadata Request with a mix of existing and
non-existing topics.

The particular codepath was not exercised by a test in the original PR.
@ijuma fixed the code path on merge
This small testcase covers that

Co-authored-by: Edoardo Comar ecomar@uk.ibm.com
Co-authored-by: Mickael Maison mickael.maison@gmail.com

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Summary of testing strategy (including rationale)
for the feature or bug fix. Unit and/or integration
tests are expected for any behaviour change and
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[edoardocomar]

@ijuma I have rebased this PR a few times. would you like to merge it ? thanks

[ijuma]

LGTM. I assume this test fails if we make the change that we had in the previous PR?

[edoardocomar]

thanks @ijuma - yes this test failed without this fix dc2727e of yours in the other PR

[edoardocomar]

Hi @ijuma I thought you were going to commit to the 2.0 branch as well ?

[ijuma]

I only merged to trunk. PRs target trunk so the benefit of backporting seems minimal.

[edoardocomar]

I am not sure I understand ... KIP-277 is in 2.0, #4795 was committed to trunk before the 2.0 branch was created.
So I think the test gap could be closed there as well

[edoardocomar]

@ijuma ^

[ijuma]

The testing gap existed previously though. By your logic, every time we find a testing gap, we need to backport the fix to every branch. In any case, since you seem to care a lot about this (even if the reason is unclear to me), I will cherry-pick it to 2.0 (it's harmless, but taking committer time on something with minimal benefit compared to other things).

[edoardocomar]

I understand that committer time is a scarce resource, but I thought the testing gap was due to the introduction of KIP-277 in 2.0.