private static StoreFlushContext flushStore(HStore store, long id) throws IOException {
    StoreFlushContext storeFlushCtx = store.createFlushContext(id, FlushLifeCycleTracker.DUMMY);
    storeFlushCtx.prepare();
    storeFlushCtx.flushCache(Mockito.mock(MonitoredTask.class));
    storeFlushCtx.commit(Mockito.mock(MonitoredTask.class));
    return storeFlushCtx;
  }
Faulty file system that will fail if you write past its fault position the FIRST TIME only;
thereafter it will succeed. Used by {@link TestHRegion} too.
hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestHStore.java