File storeDir = TEMP_DIR;
lookup.store(new FileOutputStream(new File(storeDir, "lookup.dat")));
// Re-read it from disk.
lookup = lookupClass.newInstance();
lookup.load(new FileInputStream(new File(storeDir, "lookup.dat")));
// Assert validity.
long previous = Long.MIN_VALUE;
for (TermFreq k : keys) {
List<LookupResult> list = lookup.lookup(_TestUtil.bytesToCharSequence(k.term, random), false, 1);