[KAFKA-15557] Investigate FetcherTest's/FetchRequestManager's duplicate metadata update in assignFromUserNoId

• Type: Test
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Component/s: clients, consumer, unit tests
• Labels: consumer-threading-refactor fetcher unit-tests
• Assignee: Unassigned
• Reporter: Kirk True
• Created: 05/Oct/23 22:12
• Updated: 07/Oct/24 04:01

Description

The unit tests FetcherTest and FetchRequestManagerTest have methods named assignFromUser() and assignFromUserNoId() that appear to perform duplicate metadata updates:

private void assignFromUser(Set<TopicPartition> partitions) {
    subscriptions.assignFromUser(partitions);
    client.updateMetadata(initialUpdateResponse);

    // A dummy metadata update to ensure valid leader epoch.
    metadata.updateWithCurrentRequestVersion(
            RequestTestUtils.metadataUpdateWithIds(
                "dummy",
                1, 
                Collections.emptyMap(),
                singletonMap(topicName, 4),
                tp -> validLeaderEpoch, topicIds
            ),
            false,
            0L
    );
}

client.updateMetadata() eventually calls metadata.updateWithCurrentRequestVersion(). Determine why the test is updating the cluster metadata twice with different values.