program example

   call init()
   call test_use()
   call finalize()

contains

   subroutine init()
      use mpi, only: MPI_Init
      implicit none
      integer :: ierr
      call MPI_Init(ierr)
   end subroutine

   subroutine finalize()
      use mpi, only: MPI_Finalize
      implicit none
      integer :: ierr
      call MPI_Finalize(ierr)
   end subroutine

   subroutine test_use()

      implicit none
#include "mpif.h"

      integer :: ierr, rank, num_ranks
      logical :: test_ok

      call MPI_COMM_RANK(MPI_COMM_WORLD, rank, ierr)
      call MPI_COMM_SIZE(MPI_COMM_WORLD, num_ranks, ierr)

      test_ok = (num_ranks == 2 .and. (rank == 0 .or. rank == 1))

      if (test_ok) then
         if (rank == 0) print *, 'PASSED'
      else
         stop "FAILED"
      endif

   end subroutine

end program