#1328: tests: Initialize MPI only once

tests/unit/main.cc

@@ -57,14 +57,11 @@ std::unique_ptr<MPISingletonMultiTest> mpi_singleton = nullptr;
 int test_argc = 0;
 char** test_argv = nullptr;
 
-}}} // end namespace vt::tests::unit
-
-bool should_init_MPI(int& argc, char** argv) {
-  if (argc < 2) {
-    return false;
+void init_MPI_if_needed(int& argc, char** argv) {
+  if (argc < 2 or (mpi_singleton != nullptr)) {
+    return;
   }
 
-
   // Extra flag (--MPI_TEST or --NO_MPI_TEST) is added as the last argument
   std::string test_arg = argv[argc - 1];
   assert(
@@ -75,19 +72,20 @@ bool should_init_MPI(int& argc, char** argv) {
   // 'Remove' the argument so we don't pass it further to vt
   --argc;
 
-  return test_arg == "--MPI_TEST";
+  if (test_arg == "--MPI_TEST") {
+    mpi_singleton = std::make_unique<MPISingletonMultiTest>(argc, argv);
+  }
 }
 
+}}} // end namespace vt::tests::unit
+
 int main(int argc, char **argv) {
 
   /**
    * Initalize MPI (if needed) before GTEST so we can check for number of ranks
    * during GTEST code generation.
    */
-  if (should_init_MPI(argc, argv)) {
-    vt::tests::unit::mpi_singleton =
-      std::make_unique<vt::tests::unit::MPISingletonMultiTest>(argc, argv);
-  }
+  vt::tests::unit::init_MPI_if_needed(argc, argv);
 
   ::testing::InitGoogleTest(&argc, argv);
 

tests/unit/test_helpers.h

@@ -115,7 +115,7 @@ inline bool isOversubscribed() {
  */
 #define SET_NUM_NODES_CONSTRAINT(req_num_nodes)                           \
 {                                                                         \
- auto const num_nodes = theContext()->getNumNodes();                      \
+  auto const num_nodes = theContext()->getNumNodes();                     \
   if (num_nodes != req_num_nodes) {                                       \
     GTEST_SKIP() << fmt::format(                                          \
       "Skipping the run on {} nodes. This test should run only on {} "    \