ObjectId pid = db.resolve("refs/heads/master");
RefUpdate updateRef = db.updateRef("refs/heads/master");
updateRef.setNewObjectId(ppid);
updateRef.setForceUpdate(true);
Result update = updateRef.update();
assertEquals(Result.FORCED, update);
assertEquals(ppid, db.resolve("refs/heads/master"));
// real test
RevCommit old = new RevWalk(db).parseCommit(ppid);
RefUpdate updateRef2 = db.updateRef("refs/heads/master");
updateRef2.setExpectedOldObjectId(old);
updateRef2.setNewObjectId(pid);
Result update2 = updateRef2.update();
assertEquals(Result.FAST_FORWARD, update2);
assertEquals(pid, db.resolve("refs/heads/master"));
}