@Test
  public void test_createSamplerAggregator() {
    Aggregator aggregator = AggregatorFactory.createSamplerAggregator();

    assertThat(aggregator.getName(), equalTo("sampler"));
  }
  @Test
  public void test_createDiffAggregator() {
    Aggregator aggregator = AggregatorFactory.createDiffAggregator();

    assertThat(aggregator.getName(), equalTo("diff"));
  }