diff -r 000000000000 -r 6474c204b198 browser/devtools/scratchpad/test/browser_scratchpad_pprint-02.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/devtools/scratchpad/test/browser_scratchpad_pprint-02.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,40 @@
+/* vim: set ts=2 et sw=2 tw=80: */
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+function test()
+{
+  waitForExplicitFinish();
+
+  gBrowser.selectedTab = gBrowser.addTab();
+  gBrowser.selectedBrowser.addEventListener("load", function onLoad() {
+    gBrowser.selectedBrowser.removeEventListener("load", onLoad, true);
+    openScratchpad(runTests);
+  }, true);
+
+  content.location = "data:text/html;charset=utf8,test Scratchpad pretty print.";
+}
+
+let gTabsize;
+
+function runTests(sw)
+{
+  gTabsize = Services.prefs.getIntPref("devtools.editor.tabsize");
+  Services.prefs.setIntPref("devtools.editor.tabsize", 6);
+  const space = " ".repeat(6);
+
+  const sp = sw.Scratchpad;
+  sp.setText("function main() { console.log(5); }");
+  sp.prettyPrint().then(() => {
+    const prettyText = sp.getText();
+    ok(prettyText.contains(space));
+    finish();
+  }).then(null, error => {
+    ok(false, error);
+  });
+}
+
+registerCleanupFunction(function () {
+  Services.prefs.setIntPref("devtools.editor.tabsize", gTabsize);
+  gTabsize = null;
+});