@Test
public void testEmitBatch() {

  spout.emitBatch(0L, collector);
  spout.emitBatch(1L, collector);
  verify(collector, times(20)).emit(any(Values.class));
  Map<Long, List<String>> batches = spout.getBatches();
  assertThat(batches)
          .hasSize(2)
          .containsKey(0L)
          .containsKey(1L);
  assertThat(batches.get(0L)).hasSize(10);
  assertThat(batches.get(1L)).hasSize(10);
}