private static void setFileStripe(HStoreFile sf, byte[] startKey, byte[] endKey) {
    when(sf.getMetadataValue(StripeStoreFileManager.STRIPE_START_KEY)).thenReturn(startKey);
    when(sf.getMetadataValue(StripeStoreFileManager.STRIPE_END_KEY)).thenReturn(endKey);
  }
This method actually does all the work.
hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/compactions/TestStripeCompactionPolicy.java