diff -r 000000000000 -r 6474c204b198 browser/devtools/debugger/test/browser_dbg_pretty-print-12.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/devtools/debugger/test/browser_dbg_pretty-print-12.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,54 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * Make sure that we don't leave the pretty print button checked when we fail to
+ * pretty print a source (because it isn't a JS file, for example).
+ */
+
+const TAB_URL = EXAMPLE_URL + "doc_blackboxing.html";
+
+let gTab, gDebuggee, gPanel, gDebugger;
+let gEditor, gSources;
+
+function test() {
+  initDebugger(TAB_URL).then(([aTab, aDebuggee, aPanel]) => {
+    gTab = aTab;
+    gDebuggee = aDebuggee;
+    gPanel = aPanel;
+    gDebugger = gPanel.panelWin;
+    gEditor = gDebugger.DebuggerView.editor;
+    gSources = gDebugger.DebuggerView.Sources;
+
+    waitForSourceShown(gPanel, "")
+      .then(() => {
+        let shown = ensureSourceIs(gPanel, TAB_URL, true)
+        gSources.selectedValue = TAB_URL;
+        return shown;
+      })
+      .then(clickPrettyPrintButton)
+      .then(testButtonIsntChecked)
+      .then(() => closeDebuggerAndFinish(gPanel))
+      .then(null, aError => {
+        ok(false, "Got an error: " + DevToolsUtils.safeErrorString(aError));
+      });
+  });
+}
+
+function clickPrettyPrintButton() {
+  gDebugger.document.getElementById("pretty-print").click();
+}
+
+function testButtonIsntChecked() {
+  is(gDebugger.document.getElementById("pretty-print").checked, false,
+     "The button shouldn't be checked after trying to pretty print a non-js file.");
+}
+
+registerCleanupFunction(function() {
+  gTab = null;
+  gDebuggee = null;
+  gPanel = null;
+  gDebugger = null;
+  gEditor = null;
+  gSources = null;
+});