libsbml.Model.addConstraint C# (CSharp) Method

        public int addConstraint(Constraint c)
        {
            int ret = libsbmlPINVOKE.Model_addConstraint(swigCPtr, Constraint.getCPtr(c));
            return ret;
        }

 public void test_Model_addConstraint3()
 {
     Model m = new  Model(2,2);
       Constraint c = null;
       int i = m.addConstraint(c);
       assertTrue( i == libsbml.LIBSBML_OPERATION_FAILED );
       assertTrue( m.getNumConstraints() == 0 );
       m = null;
 }