Add rudimentary Promise support to navigate helper

Author: mislav

test/unit/helpers.js

@@ -2,6 +2,9 @@
 // callbacks, then executes them serially with respect to async. This is to
 // avoid deep nesting of callbacks in tests.
 //
+// If a `then`able object is returned from a callback, then the navigation will
+// resume only after the promise has been resolved.
+//
 // After last successful navigation, asyncTest is automatically resumed.
 //
 // Usage:
@@ -30,8 +33,9 @@ function navigate(frame) {
     var target = item[0], callback = item[1]
 
     frame.$(frame.document).one("pjax:end", function() {
-      if (callback) callback(frame)
-      setTimeout(workOff, 0)
+      var promise = callback && callback(frame)
+      if (promise && typeof promise.then == "function") promise.then(workOff)
+      else setTimeout(workOff, 0)
     })
 
     if (typeof target == "number") {
@@ -45,3 +49,18 @@ function navigate(frame) {
 
   return api
 }
+
+// A poor man's Promise implementation. Only resolvable promises with no
+// reject/catch support.
+function PoorMansPromise(setup) {
+  var result, callback, i = 0, callbacks = []
+  setup(function(_result) {
+    result = _result
+    while (callback = callbacks[i++]) callback(result)
+  })
+  this.then = function(done) {
+    if (i == 0) callbacks.push(done)
+    else setTimeout(function(){ done(result) }, 0)
+    return this
+  }
+}