Mocking FacesContext

I am trying to add some unit tests to a JSF application. This application didnt rely heavily on any best practices, so many service methods use the FacesContext to pull data from managed session beans like so:

(this is inside a util class)

  public static Object getPageBean(String beanReference) {
      FacesContext fc = FacesContext.getCurrentInstance();
      VariableResolver vr = fc.getApplication().getVariableResolver();
      return vr.resolveVariable(fc, beanReference);
  }

What would be the best way to mock this? I am using groovy so i have a few more options for creating classes that i cant normally create.