public Fetch<K, V> collectFetch() {
        return fetchCollector.collectFetch(fetchBuffer);
    }
@Test
    public void testFetchRequestInternalError() {
        buildFetcher();
        makeFetchRequestWithIncompleteRecord();
        try {
            collectFetch();
            fail("collectFetch should have thrown a KafkaException");
        } catch (KafkaException e) {
            assertTrue(e.getMessage().startsWith("Failed to make progress reading messages"));
            // the position should not advance since no data has been returned
            assertEquals(0, subscriptions.position(tp0).offset);
        }
    }