@Test
public void testSampleRowKeysAsync() throws Exception {

  List<KeyOffset> keyOffsets =
      ImmutableList.of(
          KeyOffset.create(ByteString.copyFromUtf8("a"), 1),
          KeyOffset.create(ByteString.copyFromUtf8("z"), 1));
  when(mockDataClient.sampleRowKeysAsync(TABLE_ID))
      .thenReturn(ApiFutures.immediateFuture(keyOffsets));
  assertEquals(keyOffsets, dataClientWrapper.sampleRowKeysAsync(TABLE_ID).get());
  verify(mockDataClient).sampleRowKeysAsync(TABLE_ID);
}