@Test
public void testReport() throws Exception {

    Clock clock= Clock.defaultClock();
    reporter= builder.convertRatesTo(TimeUnit.MINUTES)
            .convertDurationsTo(TimeUnit.SECONDS)
            .withClock(clock)
            .filter(MetricFilter.ALL)
            .build();
    reporter.start(1, TimeUnit.SECONDS);
    SortedMap<String, Gauge> gauges= new TreeMap<>();
    SortedMap<String, Counter> counters= new TreeMap<>();
    SortedMap<String, Histogram> histograms= new TreeMap<>();
    SortedMap<String, Meter> meters= new TreeMap<>();
    SortedMap<String, Timer> timers= new TreeMap<>();
    Gauge gauge= new FileDescriptorRatioGauge();
    gauges.put("gauges", gauge);
    Counter counter= new Counter();
    counters.put("counters", counter);
    Meter meter= new Meter();
    meters.put("meters", meter);
    Timer timer= new Timer();
    timers.put("timers", timer);
    Exception ex= null;
    try {
        reporter.report(gauges, counters, histograms, meters, timers);
    } catch (Exception e)   {ex= e; }
    assertNull("Expected null value that means not exception", ex);
}