gistfile1.js

var waitForError = function (expectedError, done) {
    var originalExceptionListener = process.listeners("uncaughtException").pop();

    process.once("uncaughtException", function (error) {
        process.listeners("uncaughtException").push(originalExceptionListener);

        if (error instanceof expectedError) {
            done();
        } else {
            process.nextTick(function () {
                throw error;
            });
        }

    });
};