Try using pfunit's "MpiTestMethod" class.

Author: nusbaume

test/unit/fortran/src/pio_reader/test_pio_reader.pf

@@ -31,8 +31,8 @@ contains
 !PIO reader object open/close file tests
 !+++++++++++++++++++++++++++++++++++++++++++++++++++++
 
-@test
-subroutine test_pio_reader_open_close_file()
+@test(npes=[1])
+subroutine test_pio_reader_open_close_file(this)
     !Check that the PIO reader can open and
     !close a file successfully.
     !use funit
@@ -42,6 +42,8 @@ subroutine test_pio_reader_open_close_file()
     use ccpp_io_reader, only: abstract_netcdf_reader_t
     use ccpp_io_reader, only: create_netcdf_reader_t
 
+    class (MpiTestMethod), intent(inout) :: this
+
     class(abstract_netcdf_reader_t), allocatable :: reader
 
     integer            :: errcode