diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/debug/Debugger-ctor-03.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/debug/Debugger-ctor-03.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,19 @@
+// If the debuggee cannot be put into debug mode, throw.
+
+// Run this test only if this compartment can't be put into debug mode.
+var canEnable = true;
+if (typeof setDebugMode === 'function') {
+    try {
+        setDebugMode(true);
+    } catch (exc) {
+        canEnable = false;
+    }
+}
+
+if (!canEnable) {
+    var g = newGlobal();
+    g.libdir = libdir;
+    g.eval("load(libdir + 'asserts.js');");
+    g.parent = this;
+    g.eval("assertThrowsInstanceOf(function () { new Debugger(parent); }, Error);");
+}