@Override
  public void setUserGroupIfNeeded(AlluxioURI uri) {
    FuseContext fc = mFuseFileSystem.get().getContext();
    setUserGroup(uri, fc.uid.get(), fc.gid.get());
  }
@Test
  public void setUserGroupIfNeed() throws Exception {
    AlluxioURI uri = new AlluxioURI("/SetUserGroupIfNeed");
    FuseContext context = FuseContext.of(ByteBuffer.allocate(32));
    context.uid.set(UID);
    context.gid.set(GID);
    mFuseFileSystem.setContext(context);
    mAuthPolicy.setUserGroupIfNeeded(uri);
    URIStatus status = mFileSystem.getStatus(uri);
    Assert.assertEquals(USER, status.getOwner());
    Assert.assertEquals(GROUP, status.getGroup());
  }