From e5715946c278b552866849cf5d54c07a7cae4b3b Mon Sep 17 00:00:00 2001
From: Paul Romano <paul.k.romano@gmail.com>
Date: Wed, 21 Apr 2021 10:40:01 -0500
Subject: [PATCH] Make sure cpp_driver test works with MPI

---
 tests/regression_tests/cpp_driver/driver.cpp | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/tests/regression_tests/cpp_driver/driver.cpp b/tests/regression_tests/cpp_driver/driver.cpp
index 3b4bd1daa2..995d91e084 100644
--- a/tests/regression_tests/cpp_driver/driver.cpp
+++ b/tests/regression_tests/cpp_driver/driver.cpp
@@ -1,6 +1,10 @@
+#ifdef OPENMC_MPI
+#include <mpi.h>
+#endif
 
 #include "openmc/capi.h"
 #include "openmc/cell.h"
+#include "openmc/error.h"
 #include "openmc/geometry.h"
 #include "openmc/message_passing.h"
 #include "openmc/summary.h"
@@ -11,7 +15,13 @@
 using namespace openmc;
 
 int main(int argc, char** argv) {
-  openmc_init(argc, argv, nullptr);
+#ifdef OPENMC_MPI
+  MPI_Comm world {MPI_COMM_WORLD};
+  int err = openmc_init(argc, argv, &world);
+#else
+  int err = openmc_init(argc, argv, nullptr);
+#endif
+  if (err) fatal_error(openmc_err_msg);
 
   // create a new cell filter
   auto cell_filter = Filter::create<CellFilter>();
@@ -57,5 +67,10 @@ int main(int argc, char** argv) {
 
   openmc_run();
   openmc_finalize();
+
+#ifdef OPENMC_MPI
+  MPI_Finalize();
+#endif
+
   return 0;
 }