drain

A way to help test async code.

A place to pour your completed events.

A way to help with coordinating async tasks.

A way to crash your node process if something hasn't happend within timeframe.

Examples

Simple:

var drain = new Drain(3);
drain.on('full', function() {
  console.log('we done here');
});

drain.add();
drain.add();
console.log("hai!");
drain.add();

/* program output
  hai!
  we done here
*/

Async:

var drain = new Drain(4, function() {
  console.log('bird');
  console.log('yeah');
});

setTimeout(function() { 
  console.log('mock');
  drain.add();
  setTimeout(function() {
    console.log('yeah');
    drain.add();
    setTimeout(function() {
      console.log('ing');
      drain.add();
      setTimeout(function() {
        console.log('yeah');
        drain.add();
      }, 100);
    }, 100);
  }, 100);       
}, 100);

/* program output
  mock
  yeah
  ing
  yeah
  bird
  yeah
*/

Timeouts (default 1 second)

When drain doesn't have an add() called within a certain timeout, drain will raise an 'error' event. This is intended to be uncaught and crash your test case but you can catch it if you'd rather...

var drain = new Drain(3);

/*
  program crashes with uncaught exception after ~1 second
*/

Or how about this?

var drain = new Drain(3);
setTimeout(drain.add.bind(drain), 500);
setTimeout(drain.add.bind(drain), 1000);
//oh man we only need to add one more...but we don't...

/*
  program crashes with unhandled 'error' event after ~2 seconds
*/

okay so how does this help me?

Let's test an http request & response using Drain

var http = require('http');

var server = http.createServer(function(req, res) {
  res.writeHead(200, {"Content-Type" : "text/plain"} );
  res.end("hai!");
});
server.listen(3000);

http.request('get', 'http://localhost:3000', function(response) {
  drain.set();
});

var drain = new Drain(1, function() {
  server.end();
});

Now our test wont hang forever if the request doesn't come back. At least all this...is the eventual goal