diff -r 000000000000 -r 6474c204b198 browser/devtools/webconsole/test/browser_webconsole_chrome.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/devtools/webconsole/test/browser_webconsole_chrome.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,36 @@
+/* vim:set ts=2 sw=2 sts=2 et: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Tests that code completion works properly in chrome tabs, like about:credits.
+
+function test() {
+  Task.spawn(function*() {
+    const {tab} = yield loadTab("about:config");
+    ok(tab, "tab loaded");
+
+    const hud = yield openConsole(tab);
+    ok(hud, "we have a console");
+    ok(hud.iframeWindow, "we have the console UI window");
+
+    let jsterm = hud.jsterm;
+    ok(jsterm, "we have a jsterm");
+
+    let input = jsterm.inputNode;
+    ok(hud.outputNode, "we have an output node");
+
+    // Test typing 'docu'.
+    input.value = "docu";
+    input.setSelectionRange(4, 4);
+
+    let deferred = promise.defer();
+
+    jsterm.complete(jsterm.COMPLETE_HINT_ONLY, function() {
+      is(jsterm.completeNode.value, "    ment", "'docu' completion");
+      deferred.resolve(null);
+    });
+
+    yield deferred.promise;
+  }).then(finishTest);
+}