writer.close();
long gen = SegmentInfos.getLastCommitGeneration(dir);
assertTrue("segment generation should be > 0 but got " + gen, gen > 0);
String[] files = dir.listAll();
boolean corrupted = false;
for(int i=0;i<files.length;i++) {
if (files[i].endsWith(".cfs")) {
dir.deleteFile(files[i]);
corrupted = true;