add test for loading multiple tif files
add test for loading multiple tif files

thunder-project/thunder,pearsonlab/thunder,oliverhuangchao/thunder,broxtronix/thunder,zhwa/thunder,j-friedrich/thunder,kcompher/thunder,j-friedrich/thunder,jwittenbach/thunder,zhwa/thunder,kcompher/thunder,oliverhuangchao/thunder,kunallillaney/thunder,broxtronix/thunder,poolio/thunder,pearsonlab/thunder,mikarubi/thunder,poolio/thunder,mikarubi/thunder,kunallillaney/thunder