program main
#include <petsc/finclude/petscsys.h>
      use petscsys
      implicit none
      character(len=256) :: filename
      character(len=1)   :: mode
      PetscBool          :: exists
      PetscErrorCode     :: ierr
      PetscCallA(PetscInitialize(ierr))
      filename = 'filename'
      mode = 'r'
      PetscCallA(PetscTestFile(filename, mode, exists, ierr))
      write(*, '(A, A, A, I0)') "File ", trim(filename), " doesn't exist = ", merge(1, 0, exists)
      PetscCallA(PetscFinalize(ierr))
      end
!/*TEST
!
!   test:
!
!TEST*/