From 896a689e84327795d2c26a5fd40119dfbde21db7 Mon Sep 17 00:00:00 2001
From: Benjamin Keen <ben.keen@gmail.com>
Date: Thu, 4 Dec 2014 15:01:20 -0800
Subject: [PATCH] New waitForAttribute nightwatch helper

This test allows us to not just wait for an element, but for an
element attribute containing a certain value. This can be helpful in a
number of scenarios, like when a JS event changes the content of a page
but the DOM structure remains largely the same (e.g. a form).
---
 .../custom-commands/waitForAttribute.js       | 57 +++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100644 test/nightwatch_tests/custom-commands/waitForAttribute.js

diff --git a/test/nightwatch_tests/custom-commands/waitForAttribute.js b/test/nightwatch_tests/custom-commands/waitForAttribute.js
new file mode 100644
index 000000000..429a9b526
--- /dev/null
+++ b/test/nightwatch_tests/custom-commands/waitForAttribute.js
@@ -0,0 +1,57 @@
+var util = require('util');
+var events = require('events');
+
+/*
+ * This custom command allows us to locate an HTML element on the page and then wait until the value of a specified
+ * attribute matches the provided expression (aka. the 'checker' function). It retries executing the checker function
+ * every 100ms until either it evaluates to true or it reaches maxTimeInMilliseconds (which fails the test).
+ * Nightwatch uses the Node.js EventEmitter pattern to handle asynchronous code so this command is also an EventEmitter.
+ */
+
+function WaitForAttribute() {
+  events.EventEmitter.call(this);
+  this.startTimeInMilliseconds = null;
+}
+
+util.inherits(WaitForAttribute, events.EventEmitter);
+
+WaitForAttribute.prototype.command = function (element, attribute, checker, timeoutInMilliseconds) {
+  this.startTimeInMilliseconds = new Date().getTime();
+  var self = this;
+  var message;
+
+  if (typeof timeoutInMilliseconds !== 'number') {
+    timeoutInMilliseconds = 8000;
+  }
+
+  this.check(element, attribute, checker, function (result, loadedTimeInMilliseconds) {
+    if (result) {
+      message = 'waitForAttribute: ' + element + '@' + attribute + '. Expression was true after ' + (loadedTimeInMilliseconds - self.startTimeInMilliseconds) + ' ms.';
+    } else {
+      message = 'waitForAttribute: ' + element + '@' + attribute + '. Expression wasn\'t true in ' + timeoutInMilliseconds + ' ms.';
+    }
+    self.client.assertion(result, 'expression false', 'expression true', message, true);
+    self.emit('complete');
+  }, timeoutInMilliseconds);
+
+  return this;
+};
+
+WaitForAttribute.prototype.check = function (element, attribute, checker, callback, maxTimeInMilliseconds) {
+  var self = this;
+
+  this.api.getAttribute(element, attribute, function (result) {
+    var now = new Date().getTime();
+    if (result.status === 0 && checker(result.value)) {
+      callback(true, now);
+    } else if (now - self.startTimeInMilliseconds < maxTimeInMilliseconds) {
+      setTimeout(function () {
+        self.check(element, attribute, checker, callback, maxTimeInMilliseconds);
+      }, 100);
+    } else {
+      callback(false);
+    }
+  });
+};
+
+module.exports = WaitForAttribute;