text: // test that a rollback of an op with empty ns causes a message to be logged
  //
  // If all data-bearing nodes in a replica set are using an ephemeral storage engine, the set will
  // not be able to survive a scenario where all data-bearing nodes are down simultaneously. In such a
  // scenario, none of the members will have any data, and upon restart will each look for a member to
  // inital sync from, so no primary will be elected. This test induces such a scenario, so cannot be
  // run on ephemeral storage engines.
  // @tags: [requires_persistence]
  
  // function to check the logs for an entry
  doesEntryMatch = function(array, regex) {
      var found = false;
      for (i = 0; i < array.length; i++) {
          if (regex.test(array[i])) {
              found = true;
          }
      }
      return found;
  }
  
  // set up a set and grab things for later
  var name = "rollback_empty_ns";
  var replTest = new ReplSetTest({name: name, nodes: 3});
  var nodes = replTest.nodeList();
  var conns = replTest.startSet();
  replTest.initiate({"_id": name,
                     "members": [
                         { "_id": 0, "host": nodes[0], priority: 3 },
                         { "_id": 1, "host": nodes[1] },
                         { "_id": 2, "host": nodes[2], arbiterOnly: true}]
                    });
  var a_conn = conns[0];
  var b_conn = conns[1];
  var AID = replTest.getNodeId(a_conn);
  var BID = replTest.getNodeId(b_conn);
  
  replTest.waitForState(replTest.nodes[0], ReplSetTest.State.PRIMARY, 60 * 1000);
  
  // get master and do an initial write
  var master = replTest.getPrimary();
  assert(master === conns[0], "conns[0] assumed to be master");
  assert(a_conn.host === master.host, "a_conn assumed to be master");
  var options = {writeConcern: {w: 2, wtimeout: 60000}, upsert: true};
  assert.writeOK(a_conn.getDB(name).foo.insert({x: 1}, options));
  
  // shut down master
  replTest.stop(AID);
  
  // insert a fake oplog entry with an empty ns
  master = replTest.getPrimary();
  assert(b_conn.host === master.host, "b_conn assumed to be master");
  options = {writeConcern: {w: 1, wtimeout: 60000}, upsert: true};
  // another insert to set minvalid ahead
  assert.writeOK(b_conn.getDB(name).foo.insert({x: 123}));
  var oplog_entry = b_conn.getDB("local").oplog.rs.find().sort({$natural: -1})[0];
  oplog_entry["ts"] = Timestamp(oplog_entry["ts"].t, oplog_entry["ts"].i + 1);
  oplog_entry["ns"] = "";
  assert.writeOK(b_conn.getDB("local").oplog.rs.insert(oplog_entry));
  
  // shut down B and bring back the original master
  replTest.stop(BID);
  replTest.restart(AID);
  master = replTest.getPrimary();
  assert(a_conn.host === master.host, "a_conn assumed to be master");
  
  // do a write so that B will have to roll back
  options = {writeConcern: {w: 1, wtimeout: 60000}, upsert: true};
  assert.writeOK(a_conn.getDB(name).foo.insert({x: 2}, options));
  
  // restart B, which should rollback and log a message about not rolling back empty ns'd oplog entry
  replTest.restart(BID);
  var msg = RegExp("ignoring op on rollback no ns TODO : ");
  assert.soon(function() {
      try {
          var log = b_conn.getDB("admin").adminCommand({getLog: "global"}).log;
          return doesEntryMatch(log, msg);
      }
      catch (e) {
          return false;
      }
  }, "Did not see a log entry about skipping the empty ns'd oplog entry during rollback");
  
  replTest.stopSet();
  