diff -r 000000000000 -r 6474c204b198 browser/devtools/sourceeditor/test/browser_editor_history.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/devtools/sourceeditor/test/browser_editor_history.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,32 @@
+/* vim: set ts=2 et sw=2 tw=80: */
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+function test() {
+  waitForExplicitFinish();
+  setup((ed, win) => {
+    ok(ed.isClean(), "default isClean");
+    ok(!ed.canUndo(), "default canUndo");
+    ok(!ed.canRedo(), "default canRedo");
+
+    ed.setText("Hello, World!");
+    ok(!ed.isClean(), "isClean");
+    ok(ed.canUndo(), "canUndo");
+    ok(!ed.canRedo(), "canRedo");
+
+    ed.undo();
+    ok(ed.isClean(), "isClean after undo");
+    ok(!ed.canUndo(), "canUndo after undo");
+    ok(ed.canRedo(), "canRedo after undo");
+
+    ed.setText("What's up?");
+    ed.setClean();
+    ok(ed.isClean(), "isClean after setClean");
+    ok(ed.canUndo(), "canUndo after setClean");
+    ok(!ed.canRedo(), "canRedo after setClean");
+
+    teardown(ed, win);
+  });
+}
\ No newline at end of file