@Test
  public void testDiskCounters() throws InterruptedException {
    final long startTime = statisticsClock.getTime();

    diskRegionStats.incNumEntriesInVM(10);
    diskRegionStats.incNumOverflowOnDisk(15);
    diskRegionStats.startWrite();
    diskRegionStats.incWrittenBytes(1000);

    sample();

    assertEquals(1, getTotalDiskWritesProgress());
    assertEquals(10, getTotalDiskEntriesInVM());
    assertEquals(15, getTotalEntriesOnlyOnDisk());

    diskRegionStats.endWrite(startTime, statisticsClock.getTime());
    diskRegionStats.endRead(startTime, statisticsClock.getTime(), 1000);

    sample();

    assertTrue(getDiskReadsRate() > 0);
    assertTrue(getDiskReadsAverageLatency() > 0);

    assertTrue(getDiskWritesRate() > 0);
    assertTrue(getDiskWritesAverageLatency() > 0);
  }
Implementing RegionMXBean to ensure test coverage
geode-core/src/integrationTest/java/org/apache/geode/management/bean/stats/RegionStatsJUnitTest.java