public void test_Compartment_parent_NULL()
        {
            SBMLDocument d  = new SBMLDocument();
            Model        m  = d.createModel();
            Compartment  c  = m.createCompartment();
            Compartment  c1 = c.clone();

            d = null;
            assertTrue(c1.getAncestorOfType(libsbml.SBML_MODEL) == null);
            assertTrue(c1.getParentSBMLObject() == null);
            assertEquals(c1.getSBMLDocument(), null);
            c1 = null;
        }