mongo/jstests/replsets/replsetprio1.js

// should check that election happens in priority order

(function() {
    "use strict";
    var replTest = new ReplSetTest( {name: 'testSet', nodes: 3} );
    var nodenames = replTest.nodeList();

    var nodes = replTest.startSet();
    replTest.initiate({"_id" : "testSet",
                "members" : [
                             {"_id" : 0, "host" : nodenames[0], "priority" : 1},
                             {"_id" : 1, "host" : nodenames[1], "priority" : 2},
                             {"_id" : 2, "host" : nodenames[2], "priority" : 3}]});

    // 2 should be master (give this a while to happen, as 0 will be elected, then demoted)
    replTest.waitForState(nodes[2], ReplSetTest.State.PRIMARY, 120000);

    // kill 2, 1 should take over
    replTest.stop(2);

    // 1 should eventually be master
    replTest.waitForState(nodes[1], ReplSetTest.State.PRIMARY, 60000);
    
    // do some writes on 1
    var master = replTest.getPrimary();
    for (var i=0; i<1000; i++) {
        master.getDB("foo").bar.insert({i:i});
    }

    for (i=0; i<1000; i++) {
        master.getDB("bar").baz.insert({i:i});
    }

    // bring 2 back up, 2 should wait until caught up and then become master
    replTest.restart(2);
    replTest.waitForState(nodes[2], ReplSetTest.State.PRIMARY, 60000);

    // make sure nothing was rolled back
    master = replTest.getPrimary();
    for (i=0; i<1000; i++) {
        assert(master.getDB("foo").bar.findOne({i:i}) != null, 'checking '+i);
        assert(master.getDB("bar").baz.findOne({i:i}) != null, 'checking '+i);
    }
}());