Adding test files for the cpp driver test.

tests/regression_tests/cpp_driver/driver.cpp

@@ -0,0 +1,35 @@
+
+#include "openmc/capi.h"
+#include "openmc/cell.h"
+#include "openmc/tallies/filter.h"
+#include "openmc/tallies/filter_cell.h"
+#include "openmc/tallies/tally.h"
+
+using namespace openmc;
+
+int main(int argc, char** argv) {
+  openmc_init(argc, argv, nullptr);
+
+  // create a new cell filter
+  auto cell_filter = Filter::create<CellFilter>();
+
+  // add all cells to the cell filter
+  std::vector<int32_t> cell_indices;
+  for (auto& entry : openmc::model::cell_map) {
+      cell_indices.push_back(entry.second);
+  }
+  // sort to make sure the cell bins appear in the same
+  // order as the test relying on the openmc exe
+  std::sort(cell_indices.begin(), cell_indices.end());
+  cell_filter->set_cells(cell_indices);
+
+  // create a new tally
+  auto tally = Tally::create();
+  std::vector<Filter*> filters = {cell_filter};
+  tally->set_filters(filters);
+  tally->set_scores({"flux"});
+
+  openmc_run();
+  openmc_finalize();
+  return 0;
+}