'use strict';
const common = require('../common');

const assert = require('assert');
const dgram = require('dgram');

const client = dgram.createSocket('udp4');

client.bind(0, common.mustCall(function() {
  client.connect(client.address().port, common.mustCall(() => {
    client.on('message', common.mustCall(callback));
    const buf = Buffer.alloc(1);

    const interval = setInterval(function() {
      client.send(buf, 0, 0, common.mustCall(callback));
    }, 10);

    function callback(firstArg) {
      // If client.send() callback, firstArg should be null.
      // If client.on('message') listener, firstArg should be a 0-length buffer.
      if (firstArg instanceof Buffer) {
        assert.strictEqual(firstArg.length, 0);
        clearInterval(interval);
        client.close();
      }
    }
  }));
}));