In some projects, we need programmaticly access to the resourceBundle defined in the faces-config.xml.
FacesContext context = FacesContext.getCurrentInstance();
Application application = context.getApplication();
ResourceBundle rb = application.getResourceBundle(context, "msg");
If during a test, the code is called that looks up the resource bundle, a NullPointerException is throw since the resouce bundle isn't found.