privateStringMethod.setAccessible(true);
long returnValue = (Long) privateStringMethod.invoke(metrics);
assertEquals(THREAD_COUNT * OPERATIONS_PER_THREAD, returnValue);
metrics.doUpdates(null);
assertEquals(THREAD_COUNT * OPERATIONS_PER_THREAD,
metrics.numCreateDirOps.getPreviousIntervalValue());
assertEquals(THREAD_COUNT * OPERATIONS_PER_THREAD,
metrics.numCreateFileOps.getPreviousIntervalValue());