tenfourfox/devtools/server/tests/mochitest/setup-in-child.js

const {Cc, Ci} = require("chrome");
const cpmm = Cc["@mozilla.org/childprocessmessagemanager;1"].
  getService(Ci.nsIMessageListenerManager);
const { DebuggerServer } = require("devtools/server/main");

exports.setupChild = function (a, b, c) {
  cpmm.sendAsyncMessage("test:setupChild", [a, b, c]);
}

exports.callParent = function () {
  // Hack! Fetch DebuggerServerConnection objects directly within DebuggerServer guts.
  for (let id in DebuggerServer._connections) {
    let conn = DebuggerServer._connections[id];
    conn.setupInParent({
      module: "chrome://mochitests/content/chrome/devtools/server/tests/mochitest/setup-in-parent.js",
      setupParent: "setupParent",
      args: [{one: true}, 2, "three"]
    });
  }
}