private Partition mockPartition(TopicIdPartition topicIdPartition) {
        TopicPartition tp = topicIdPartition.topicPartition();
        Partition partition = mock(Partition.class);
        UnifiedLog log = mock(UnifiedLog.class);
        when(partition.topicPartition()).thenReturn(tp);
        when(partition.topic()).thenReturn(tp.topic());
        when(log.remoteLogEnabled()).thenReturn(true);
        when(partition.log()).thenReturn(Option.apply(log));
        return partition;
    }
This test asserts that the newly elected leader for a partition is able to find the log-start-offset.
Note that the case tested here is that the previous leader deleted the log segments up-to offset 500. And, the
log-start-offset didn't propagate to the replicas before the leader-election.
core/src/test/java/kafka/log/remote/RemoteLogManagerTest.java