anchor.diff:    order = 1
     num_variables = 4
     ierr = xc_eval_setup(id, XC_N_NX_NY_NZ, XC_CONTRACTED, order)
  -  if (ierr /= 0) then
  -    print *, 'xc_eval_setup failed with error ', ierr
  -    stop 1
  -  endif
  +  call assert(ierr == 0, "xc_eval_setup failed")
   
     vector_length = 2**order
     allocate (density(vector_length, num_variables, num_points))
  
positive.code:   real(8), allocatable :: output_array(:, :)
    real(8), allocatable :: res_reference(:)
  
    ! print some info and copyright about the library
    ! please always include this info in your code
    call xcfun_splash(text)
  
negative.code:   order = 2
    num_variables = 4
    ierr = xc_eval_setup(id, XC_N_NX_NY_NZ, XC_CONTRACTED, order)
    call assert(ierr == 0, "xc_eval_setup failed")
  
    vector_length = 2**order
    allocate (density(vector_length, num_variables, num_points))
  