diff -r 000000000000 -r 6474c204b198 dom/system/tests/worker_constants.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/system/tests/worker_constants.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,76 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+function log(text) {
+  dump("WORKER "+text+"\n");
+}
+
+function send(message) {
+  self.postMessage(message);
+}
+
+self.onmessage = function(msg) {
+  self.onmessage = function(msg) {
+    log("ignored message "+JSON.stringify(msg.data));
+  };
+  let { isDebugBuild, umask } = msg.data;
+  try {
+    test_name();
+    test_xul();
+    test_debugBuildWorkerThread(isDebugBuild);
+    test_umaskWorkerThread(umask);
+  } catch (x) {
+    log("Catching error: " + x);
+    log("Stack: " + x.stack);
+    log("Source: " + x.toSource());
+    ok(false, x.toString() + "\n" + x.stack);
+  }
+  finish();
+};
+
+function finish() {
+  send({kind: "finish"});
+}
+
+function ok(condition, description) {
+  send({kind: "ok", condition: condition, description:description});
+}
+function is(a, b, description) {
+  send({kind: "is", a: a, b:b, description:description});
+}
+function isnot(a, b, description) {
+  send({kind: "isnot", a: a, b:b, description:description});
+}
+
+// Test that OS.Constants.Sys.Name is defined
+function test_name() {
+  isnot(null, OS.Constants.Sys.Name, "OS.Constants.Sys.Name is defined");
+}
+
+// Test that OS.Constants.Sys.DEBUG is set properly in ChromeWorker thread
+function test_debugBuildWorkerThread(isDebugBuild) {
+  is(isDebugBuild, !!OS.Constants.Sys.DEBUG, "OS.Constants.Sys.DEBUG is set properly on worker thread");
+}
+
+// Test that OS.Constants.Sys.umask is set properly in ChromeWorker thread
+function test_umaskWorkerThread(umask) {
+  is(umask, OS.Constants.Sys.umask,
+     "OS.Constants.Sys.umask is set properly on worker thread: " +
+     ("0000"+umask.toString(8)).slice(-4));
+}
+
+// Test that OS.Constants.Path.libxul lets us open libxul
+function test_xul() {
+  let lib;
+  isnot(null, OS.Constants.Path.libxul, "libxul is defined");
+  try {
+    lib = ctypes.open(OS.Constants.Path.libxul);
+    lib.declare("DumpJSStack", ctypes.default_abi, ctypes.void_t);
+  } catch (x) {
+    ok(false, "test_xul: Could not open libxul: " + x);
+  }
+  if (lib) {
+    lib.close();
+  }
+  ok(true, "test_xul: opened libxul successfully");
+}