diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/debug/Environment-setVariable-01.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/debug/Environment-setVariable-01.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,9 @@
+// Environment.prototype.setVariable can set global variables.
+
+var g = newGlobal();
+var dbg = Debugger(g);
+dbg.onDebuggerStatement = function (frame) {
+    frame.environment.setVariable("x", 2);
+};
+g.eval("var x = 1; debugger;");
+assertEq(g.x, 2);