allow MPI parallel execution

src/test/test_IO.f90

@@ -1,5 +1,6 @@
 module test_IO
   use prec
+  use parallelization
   use IO
 
   implicit none(type,external)
@@ -14,24 +15,25 @@ subroutine test_IO_run()
   real, dimension(30) :: rnd_real
   character(len=size(rnd_real)) :: rnd_str
   character(len=pSTRLEN), dimension(1) :: strarray_out
-  character(len=:), allocatable :: str_out
+  character(len=:), allocatable :: str_out, fname
   integer :: u,i
 
 
   call IO_selfTest()
 
   call random_number(rnd_real)
+  fname = 'test'//IO_intAsStr(worldrank)//'.txt'
 
   do i = 1, size(rnd_real)
     rnd_str(i:i) = char(32 + int(rnd_real(i)*(127.-32.)))
   end do
-  open(newunit=u,file='test.txt',status='replace',form='formatted')
+  open(newunit=u,file=fname,status='replace',form='formatted')
   write(u,'(a)') rnd_str
   close(u)
 
-  str_out = IO_read('test.txt')
+  str_out = IO_read(fname)
   if (rnd_str//IO_EOL /= str_out) error stop 'IO_read'
-  strarray_out = IO_readlines('test.txt')
+  strarray_out = IO_readlines(fname)
   if (rnd_str /= strarray_out(1)) error stop 'IO_readlines'
 
 end subroutine test_IO_run