// Tests whether a split and a migrate in a sharded cluster preserve the epoch\

load("jstests/sharding/libs/find_chunks_util.js");

var st = new ShardingTest({shards: 2, mongos: 1});
// Balancer is by default stopped, thus it will not interfere

var config = st.s.getDB("config");
var admin = st.s.getDB("admin");
var coll = st.s.getCollection("foo.bar");

// First enable sharding
admin.runCommand({enableSharding: coll.getDB() + ""});
st.ensurePrimaryShard(coll.getDB().getName(), st.shard1.shardName);
admin.runCommand({shardCollection: coll + "", key: {_id: 1}});

var primary = config.databases.find({_id: coll.getDB() + ""}).primary;
var notPrimary = null;
config.shards.find().forEach(function(doc) {
    if (doc._id != primary)
        notPrimary = doc._id;
});

var originalUuid = config.collections.findOne({_id: coll + ""}).uuid;
var originalEpoch = config.collections.findOne({_id: coll + ""}).lastmodEpoch;

// Now do a split
printjson(admin.runCommand({split: coll + "", middle: {_id: 0}}));

assert.eq(originalUuid, config.collections.findOne({_id: coll + ""}).uuid);
assert.eq(originalEpoch, config.collections.findOne({_id: coll + ""}).lastmodEpoch);

// Now do a migrate
printjson(admin.runCommand({moveChunk: coll + "", find: {_id: 0}, to: notPrimary}));

assert.eq(originalUuid, config.collections.findOne({_id: coll + ""}).uuid);
assert.eq(originalEpoch, config.collections.findOne({_id: coll + ""}).lastmodEpoch);

st.stop();