MongoError: MongoClient must be connected before calling MongoClient.prototype.db
var MongoClient = require('mongodb').MongoClient;
MongoClient.connect("mongodb://localhost:50000,localhost:50001/integration_test_?w=0&readPreference=secondary", function(err, db) {
test.equal(null, err);
test.ok(db != null);
db.collection("replicaset_mongo_client_collection").update({a:1}, {b:1}, {upsert:true}, function(err, result) {
test.equal(null, err);
test.equal(1, result);
db.close();
test.done();
});
});