@Test
    public void testAbortTransactionFindLeaderAfterDisconnect() throws Exception {
        MockTime time = new MockTime();
        int retryBackoffMs = 100;
        Cluster cluster = mockCluster(3, 0);
        Map<String, Object> configOverride = newStrMap(AdminClientConfig.RETRY_BACKOFF_MS_CONFIG, "" + retryBackoffMs);

        try (AdminClientUnitTestEnv env = new AdminClientUnitTestEnv(time, cluster, configOverride)) {
            TopicPartition topicPartition = new TopicPartition("foo", 13);
            AbortTransactionSpec abortSpec = new AbortTransactionSpec(
                topicPartition, 12345L, (short) 15, 200);
            Iterator<Node> nodeIterator = env.cluster().nodes().iterator();
            Node firstLeader = nodeIterator.next();

            expectMetadataRequest(env, topicPartition, firstLeader);

            WriteTxnMarkersResponse response = writeTxnMarkersResponse(abortSpec, Errors.NONE);
            env.kafkaClient().prepareResponseFrom(
                request -> {
                    // We need a sleep here because the client will attempt to
                    // backoff after the disconnect
                    time.sleep(retryBackoffMs);
                    return request instanceof WriteTxnMarkersRequest;
                },
                response,
                firstLeader,
                true
            );

            Node retryLeader = nodeIterator.next();
            expectMetadataRequest(env, topicPartition, retryLeader);

            env.kafkaClient().prepareResponseFrom(
                request -> request instanceof WriteTxnMarkersRequest,
                response,
                retryLeader
            );

            AbortTransactionResult result = env.adminClient().abortTransaction(abortSpec);
            assertNull(result.all().get());
        }
    }
Test that we propagate exceptions encountered when fetching metadata.
clients/src/test/java/org/apache/kafka/clients/admin/KafkaAdminClientTest.java