diff -r 000000000000 -r 6474c204b198 webapprt/test/chrome/browser_download.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/webapprt/test/chrome/browser_download.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,58 @@
+Cu.import("resource://gre/modules/Services.jsm");
+
+let winObserver = function(win, topic) {
+  if (topic == "domwindowopened") {
+    win.addEventListener("load", function onLoadWindow() {
+      win.removeEventListener("load", onLoadWindow, false);
+
+      if (win.document.documentURI ==
+          "chrome://mozapps/content/downloads/unknownContentType.xul") {
+        ok(true, "Download dialog shown");
+
+        setTimeout(() => {
+          let button = win.document.documentElement.getButton("accept");
+          button.disabled = false;
+          win.document.documentElement.acceptDialog();
+        }, 0);
+      }
+    }, false);
+  }
+}
+
+Services.ww.registerNotification(winObserver);
+
+let MockFilePicker = SpecialPowers.MockFilePicker;
+MockFilePicker.init(window);
+MockFilePicker.useAnyFile();
+MockFilePicker.showCallback = function() {
+  ok(true, "File picker shown");
+  return MockFilePicker.returnOK;
+}
+
+let downloadListener = {
+  onDownloadStateChange: function(aState, aDownload) {
+    if (aDownload.state == Services.downloads.DOWNLOAD_FINISHED) {
+      ok(aDownload.targetFile.exists(), "Download completed");
+      is(aDownload.targetFile.fileSize, 154, "Downloaded file has correct size");
+
+      finish();
+    }
+  },
+};
+
+Services.downloads.addListener(downloadListener);
+
+registerCleanupFunction(function() {
+  Services.wm.getMostRecentWindow("Download:Manager").close();
+  Services.ww.unregisterNotification(winObserver);
+  MockFilePicker.cleanup();
+  Services.downloads.removeListener(downloadListener);
+});
+
+function test() {
+  waitForExplicitFinish();
+
+  loadWebapp("download.webapp", undefined, function onLoad() {
+    gAppBrowser.contentDocument.getElementById("download").click();
+  });
+}