added Mocha Test

simplQueue.js

+function SimplQueue(finisher) {
+  this._finisher = finisher;
+  this._queue = [];
+  this._started = false;
+}
+SimplQueue.prototype.push = function (cb) {
+  this._queue.push(cb);
+  if (this._finisher && !this._started) {
+    this._started = true;
+    var next = this._queue.shift();
+    next(this._handler.bind(this));
+  }
+};
+
+SimplQueue.prototype.start = function () {
+  if (this._started) return;
+  this._started = true;
+  var next = this._queue.shift();
+  if (next)
+    next(this._handler.bind(this));
+  else this._finisher();
+};
+
+SimplQueue.prototype._handler = function (err) {
+  if (err) return this._finisher(err);
+  var next = this._queue.shift();
+  if (next) {
+    next(this._handler.bind(this));
+  }
+  else this._finisher(null);
+};
+
+module.exports = SimplQueue;
+
+function doStuff() {
+  var queue = new SimplQueue(function (err) {
+    console.log(err);
+    console.log("finished");
+  });
+  for (var i = 0; i < 100; i++) {
+    queue.push(function (cb) {
+      setTimeout(function () {
+        if(Math.random() > 0.9)
+          return cb(new Error("muh"));
+        console.log(+new Date());
+        cb(null);
+      }, 50)
+    })
+  }
+}
+
+doStuff();
\ No newline at end of file