The log callback parameter is hardcoded totest_metadata_log_cb instead of using thelog_cb parameter passed to the function. This makes thelog_cb parameter unused and could lead to incorrect behavior.

The logic is inverted - the test only runs when the classic protocol is NOT being used, but the test appears designed for classic consumer group protocol based on the heartbeat logs it's looking for. This should beif (test_consumer_group_protocol_classic()).

Since the partitions are monotonically increasing and cannot be deleted in Kafka, we can just usecnt to know if the partition is present in the metadata or not.

Debug statement should not be so verbose. I think its sufficient to add something like "Found new partition for the topic %s. Updating metadata.". Add topic name as well instead of just topic id.

Perform the same test in the older version of the code. Add the same log at the same place there and see if this is failing or not.

Ran the test, Its failing:
`[0147_consumer_group_consumer_mock/ 14.471s] [ do_test_setup_and_run_metadata_refresh_test:1008 ]
[0147_consumer_group_consumer_mock/ 14.471s] Creating topic rdkafkatest_rnd2504dd53625e8721_cgrp_metadata with 2 partitions
[0147_consumer_group_consumer_mock/ 14.471s] Created kafka instance 0147_consumer_group_consumer_mock#producer-48
[0147_consumer_group_consumer_mock/ 14.471s] Creating topic "rdkafkatest_rnd2504dd53625e8721_cgrp_metadata" (partitions=2, replication_factor=1, timeout=26666)
[0147_consumer_group_consumer_mock/ 14.559s] CreateTopics: duration 88.111ms
[0147_consumer_group_consumer_mock/ 14.559s] Creating consumers
[0147_consumer_group_consumer_mock/ 14.560s] Setting test timeout to 60s * 2.7
[0147_consumer_group_consumer_mock/ 14.560s] Skipping setting forbidden configuration session.timeout.ms for CONSUMER protocol.
[0147_consumer_group_consumer_mock/ 14.560s] Created kafka instance 0147_consumer_group_consumer_mock#consumer-49
[0147_consumer_group_consumer_mock/ 14.560s] Setting test timeout to 60s * 2.7
[0147_consumer_group_consumer_mock/ 14.560s] Skipping setting forbidden configuration session.timeout.ms for CONSUMER protocol.
[0147_consumer_group_consumer_mock/ 14.560s] Created kafka instance 0147_consumer_group_consumer_mock#consumer-50
[0147_consumer_group_consumer_mock/ 14.560s] Created kafka instance 0147_consumer_group_consumer_mock#producer-51
[0147_consumer_group_consumer_mock/ 14.560s] Subscribing to topic rdkafkatest_rnd2504dd53625e8721_cgrp_metadata
[

Test "0147_consumer_group_consumer_mock (do_test_setup_and_run_metadata_refresh_test:1008)" failed at 0147-consumer_group_consumer_mock.c:969:wait_for_metadata_refresh_log() at Wed Sep 17 16:17:35 2025:

Test assertion failed: "seen_metadata_log": Expected metadata refresh log not seen after partition creation and heartbeat`

Why removing this unlikely? It's more likely the partition is found in cache.

Yes but we receive change in assignments very rarely once those are assigned. This is not critical path so there is no need oflikely andunlikely IMO.

That is should be done in the critical path doesn't mean it shouldn't be done elsewhere

We can keep the likely here too

Same

Internal periods are ok, but not at the end of the log message