node/test/simple/test-cluster-worker-isconnected.js

var cluster = require('cluster');
var assert = require('assert');
var util = require('util');

if (cluster.isMaster) {
  var worker = cluster.fork();

  assert.ok(worker.isConnected(),
            "isConnected() should return true as soon as the worker has " +
            "been created.");

  worker.on('disconnect', function() {
    assert.ok(!worker.isConnected(),
              "After a disconnect event has been emitted, " +
              "isConncted should return false");
  });

  worker.on('message', function(msg) {
    if (msg === 'readyToDisconnect') {
      worker.disconnect();
    }
  })

} else {
  assert.ok(cluster.worker.isConnected(),
            "isConnected() should return true from within a worker at all " +
            "times.");

  cluster.worker.process.on('disconnect', function() {
    assert.ok(!cluster.worker.isConnected(),
              "isConnected() should return false from within a worker " +
              "after its underlying process has been disconnected from " +
              "the master");
  })

  process.send('readyToDisconnect');
}