added Casper#waitForAlert()

@@ -2025,6 +2025,19 @@ Example using the ``onTimeout`` callback::
 ``details`` is a property bag of various information that will be passed to the ``waitFor.timeout`` event, if it is emitted.
 This can be used for better error messages or to conditionally ignore some timeout events.
 
+.. index:: alert
+
+``waitForAlert()``
+-------------------------------------------------------------------------------
+
+**Signature:** ``waitForAlert(Function then[, Function onTimeout, Number timeout])``
+
+Waits until a `JavaScript alert <https://developer.mozilla.org/en-US/docs/Web/API/Window.alert>`_ is triggered. The step function will be passed the alert message in the ``response.data`` property::
+
+    casper.waitForAlert(function(response) {
+        this.echo("Alert received: " + response.data);
+    });
+
 .. _casper_waitforpopup:
 
 .. index:: Popups, New window, window.open, Tabs

@@ -2118,6 +2118,31 @@ Casper.prototype.waitFor = function waitFor(testFx, then, onTimeout, timeout, de
 };
 
 /**
+ * Waits until any alert is triggered.
+ *
+ * @param  Function  then       The next step to perform (required)
+ * @param  Function  onTimeout  A callback function to call on timeout (optional)
+ * @param  Number    timeout    The max amount of time to wait, in milliseconds (optional)
+ * @return Casper
+ */
+Casper.prototype.waitForAlert = function(then, onTimeout, timeout) {
+    "use strict";
+    if (!utils.isFunction(then)) {
+        throw new CasperError("waitForAlert() needs a step function");
+    }
+    var message;
+    function alertCallback(msg) {
+        message = msg;
+    }
+    this.once("remote.alert", alertCallback);
+    return this.waitFor(function isAlertReceived() {
+        return message !== undefined;
+    }, function onAlertReceived() {
+        this.then(this.createStep(then, {data: message}));
+    }, onTimeout, timeout);
+};
+
+/**
  * Waits for a popup page having its url matching the provided pattern to be opened
  * and loaded.
  *

@@ -23,3 +23,22 @@ casper.test.begin('alert events', 1, {
         });
     }
 });
+
+casper.test.begin("Casper.waitForAlert() waits for an alert", 1, function(test) {
+    casper.start().then(function() {
+        this.evaluate(function() {
+            setTimeout(function() {
+                alert("plop");
+            }, 500);
+        });
+    });
+
+    casper.waitForAlert(function(response) {
+        test.assertEquals(response.data, "plop",
+            "Casper.waitForAlert() can wait for an alert to be triggered");
+    });
+
+    casper.run(function() {
+        test.done();
+    });
+});