# Produce a single unit file for the docunit `du`.
	fun generate_single_docunit(du: DocUnit): String
	do
		cpt += 1
		var file = "{prefix}-{cpt}.nit"

		var f
		f = create_unitfile(file)
		f.write(du.block)
		f.close

		du.test_file = file
		return file
	end