InternalCardinalityTests#testEqualsAndHashcode failure #62540
Description
The failure can easily be reproduce with:
./gradlew ':server:test' --tests "org.elasticsearch.search.aggregations.metrics.InternalCardinalityTests.testEqualsAndHashcode" -Dtests.seed=7FFFBA60D5055C4B -Dtests.security.manager=true -Dtests.locale=ar-EG -Dtests.timezone=Europe/Saratov -Druntime.java=11
And the error looks like:
2> java.lang.AssertionError: InternalCardinality mutation should not be equal to original
Expected: not <{"fmTtJ":{"meta":{"RPdFM":"Bglpg","VLYUl":"qWMAU"},"value":50}}>
but: was <{"fmTtJ":{"meta":{"RPdFM":"Bglpg","VLYUl":"qWMAU"},"value":50}}>
at __randomizedtesting.SeedInfo.seed([7FFFBA60D5055C4B:EF0C2AD1AE21564]:0)
I had a look and the problem is as follows. Before #62480 for testing equality we were ignoring the provided bucket and were generating a string that was generated by all the elements in the runLens array. From now on we are only considering the runLens in the bucket (which I think is the right thing).
The test is mutating a HyperLogLog++ by adding new elements, unfortunately the values did not change so the resulting sketch is the same as the previous one. Before it did not fail because the original HyperLogLog++ contained more buckets.