@Override
  public Health checkNode() {
    return nodeHealthChecks.stream()
      .map(NodeHealthCheck::check)
      .reduce(Health.GREEN, HealthReducer::merge);
  }
@Test
  public void check_returns_green_status_without_any_cause_when_there_is_no_NodeHealthCheck() {
    HealthCheckerImpl underTest = new HealthCheckerImpl(nodeInformation, new NodeHealthCheck[0]);

    assertThat(underTest.checkNode()).isEqualTo(Health.GREEN);
  }