#1896: tests: use unique filenames to allow parallel testing

tests/unit/collection/test_checkpoint.extended.cc

@@ -172,7 +172,9 @@ TEST_F(TestCheckpoint, test_checkpoint_1) {
   auto num_nodes = static_cast<int32_t>(theContext()->getNumNodes());
 
   auto range = vt::Index3D(num_nodes, num_elms, 4);
-  std::string const checkpoint_name{"test_checkpoint_dir"};
+  std::string const checkpoint_name(addNumNodesToFilename(
+    "test_checkpoint_1_dir_"
+  ));
   std::string const expected_label{"test_checkpoint_1"};
 
   {
@@ -251,7 +253,9 @@ TEST_F(TestCheckpoint, test_checkpoint_in_place_2) {
   auto num_nodes = static_cast<int32_t>(theContext()->getNumNodes());
 
   auto range = vt::Index3D(num_nodes, num_elms, 4);
-  auto checkpoint_name = "test_checkpoint_dir";
+  std::string const checkpoint_name(addNumNodesToFilename(
+    "test_checkpoint_in_place_2_dir_"
+  ));
   auto proxy = vt::theCollection()->constructCollective<TestCol>(
     range, "test_checkpoint_in_place_2"
   );
@@ -323,7 +327,9 @@ TEST_F(TestCheckpoint, test_checkpoint_in_place_3) {
   auto num_nodes = static_cast<int32_t>(theContext()->getNumNodes());
 
   auto range = vt::Index3D(num_nodes, num_elms, 4);
-  auto checkpoint_name = "test_checkpoint_dir_2";
+  std::string const checkpoint_name(addNumNodesToFilename(
+    "test_checkpoint_in_place_3_dir_"
+  ));
   auto proxy = vt::theCollection()->constructCollective<TestCol>(
     range, "test_checkpoint_in_place_3"
   );
@@ -400,7 +406,9 @@ TEST_F(TestCheckpoint, test_checkpoint_no_elements_on_root_rank) {
   auto num_nodes = static_cast<int32_t>(theContext()->getNumNodes());
 
   auto range = vt::Index3D(num_nodes, num_elms, 4);
-  auto checkpoint_name = "test_null_elm_checkpoint_dir";
+  std::string const checkpoint_name(addNumNodesToFilename(
+    "test_null_elm_checkpoint_dir_"
+  ));
 
   {
     auto proxy = vt::makeCollection<TestCol>("test_checkpoint_no_elements_on_root_rank")

tests/unit/runtime/test_initialization.cc

@@ -44,6 +44,7 @@
 #include <gtest/gtest.h>
 
 #include "test_parallel_harness.h"
+#include "test_helpers.h"
 
 #include <vt/collective/startup.h>
 
@@ -170,7 +171,13 @@ TEST_F(TestInitialization, test_initialize_with_file_and_args) {
   static char cli_argument[]{"--cli_argument=100"};
   static char vt_no_terminate[]{"--vt_no_terminate"};
   static char vt_lb_name[]{"--vt_lb_name=RotateLB"};
-  static char vt_input_config[]{"--vt_input_config=test_cfg.toml"};
+
+  std::string config_file(addNumNodesToFilename("test_cfg_", ".toml"));
+  std::string config_flag("--vt_input_config=");
+  std::string config_arg = config_flag + config_file;
+  char vt_input_config[100];
+  memset(vt_input_config, 0, 100);
+  strncpy(vt_input_config, config_arg.c_str(), config_arg.size());
 
   std::vector<char *> custom_args;
   custom_args.emplace_back(prog_name);
@@ -188,7 +195,7 @@ TEST_F(TestInitialization, test_initialize_with_file_and_args) {
   int this_rank;
   MPI_Comm_rank(comm, &this_rank);
   if (this_rank == 0) {
-    std::ofstream cfg_file_{"test_cfg.toml", std::ofstream::out | std::ofstream::trunc};
+    std::ofstream cfg_file_{config_file.c_str(), std::ofstream::out | std::ofstream::trunc};
     cfg_file_ << "vt_lb_name = RandomLB\n";
     cfg_file_.close();
   }
@@ -213,7 +220,13 @@ TEST_F(TestInitialization, test_initialize_with_file_args_and_appconfig) {
   static char cli_argument[]{"--cli_argument=100"};
   static char vt_no_terminate[]{"--vt_no_terminate"};
   static char vt_lb_name[]{"--vt_lb_name=RotateLB"};
-  static char vt_input_config[]{"--vt_input_config=test_cfg.toml"};
+
+  std::string config_file(addNumNodesToFilename("test_appcfg_", ".toml"));
+  std::string config_flag("--vt_input_config=");
+  std::string config_arg = config_flag + config_file;
+  char vt_input_config[100];
+  memset(vt_input_config, 0, 100);
+  strncpy(vt_input_config, config_arg.c_str(), config_arg.size());
 
   std::vector<char*> custom_args;
   custom_args.emplace_back(prog_name);
@@ -234,7 +247,7 @@ TEST_F(TestInitialization, test_initialize_with_file_args_and_appconfig) {
   int this_rank;
   MPI_Comm_rank(comm, &this_rank);
   if (this_rank == 0) {
-    std::ofstream cfg_file_{"test_cfg.toml", std::ofstream::out | std::ofstream::trunc};
+    std::ofstream cfg_file_{config_file.c_str(), std::ofstream::out | std::ofstream::trunc};
     cfg_file_ << "vt_lb_name = RandomLB\n";
     cfg_file_.close();
   }

tests/unit/test_helpers.h

@@ -47,6 +47,7 @@
 #include "vt/context/context.h"
 #include <mpi.h>
 #include <gtest/gtest.h>
+#include <sstream>
 
 namespace vt { namespace tests { namespace unit {
 
@@ -75,6 +76,20 @@ inline bool isOversubscribed() {
   return num_ranks > CMAKE_DETECTED_MAX_NUM_NODES;
 }
 
+/**
+ * Construct a filename containing the number of ranks so that
+ * concurrently-running tests will not cause file system race conditions.
+ * Do not call this from .nompi.cc tests.
+ */
+inline std::string addNumNodesToFilename(
+  const std::string &before_num_ranks, const std::string &after_num_ranks = ""
+) {
+  auto ranks = theContext()->getNumNodes();
+  std::stringstream ss;
+  ss << before_num_ranks << ranks << after_num_ranks;
+  return ss.str();
+}
+
 /**
  * The following helper macros (these have to be macros, because GTEST_SKIP
  * won't work from nested call) are meant to ensure that the test will be

tests/unit/test_parallel_harness.h

@@ -161,6 +161,9 @@ struct TestParallelHarnessAny : TestHarnessAny<TestBase> {
    *     addArgs(vt_lb_data, vt_lb_data_dir, vt_lb_data_file);
    *   }
    * };
+   *
+   * Make sure all filenames used will be unique across all tests,
+   * parameterizations, and MPI rank counts.
    */
   virtual void addAdditionalArgs() {}
 

tests/unit/trace/test_trace_spec_reader.cc

@@ -47,6 +47,7 @@
 #include <vt/trace/file_spec/spec.h>
 
 #include "test_parallel_harness.h"
+#include "test_helpers.h"
 
 #include <fstream>
 
@@ -57,7 +58,9 @@ using TestTraceSpec = TestParallelHarness;
 TEST_F(TestTraceSpec, test_trace_spec_1) {
   using Spec = vt::trace::file_spec::TraceSpec;
 
-  std::string file_name = "test_trace_spec_1.txt";
+  std::string const file_name(addNumNodesToFilename(
+    "test_trace_spec_1_", ".txt"
+  ));
   if (theContext()->getNode() == 0) {
     std::ofstream out(file_name);
     out << ""
@@ -88,7 +91,9 @@ TEST_F(TestTraceSpec, test_trace_spec_1) {
 TEST_F(TestTraceSpec, test_trace_spec_2) {
   using Spec = vt::trace::file_spec::TraceSpec;
 
-  std::string file_name = "test_trace_spec_2.txt";
+  std::string const file_name(addNumNodesToFilename(
+    "test_trace_spec_2_", ".txt"
+  ));
   if (theContext()->getNode() == 0) {
     std::ofstream out(file_name);
     out << ""
@@ -122,7 +127,9 @@ TEST_F(TestTraceSpec, test_trace_spec_2) {
 TEST_F(TestTraceSpec, test_trace_spec_3) {
   using Spec = vt::trace::file_spec::TraceSpec;
 
-  std::string file_name = "test_trace_spec_3.txt";
+  std::string const file_name(addNumNodesToFilename(
+    "test_trace_spec_3_", ".txt"
+  ));
   if (theContext()->getNode() == 0) {
     std::ofstream out(file_name);
     out << ""
@@ -167,7 +174,9 @@ TEST_F(TestTraceSpec, test_trace_spec_3) {
 TEST_F(TestTraceSpec, test_trace_spec_4) {
   using Spec = vt::trace::file_spec::TraceSpec;
 
-  std::string file_name = "test_trace_spec_4.txt";
+  std::string const file_name(addNumNodesToFilename(
+    "test_trace_spec_4_", ".txt"
+  ));
   if (theContext()->getNode() == 0) {
     std::ofstream out(file_name);
     out << ""