Adding test files for the cpp driver test.

tests/regression_tests/cpp_driver/test.py

@@ -0,0 +1,75 @@
+from pathlib import Path
+import os
+import shutil
+import subprocess
+import textwrap
+
+import openmc
+import pytest
+
+from tests.testing_harness import PyAPITestHarness
+
+
+@pytest.fixture
+def driver(request):
+    """Compile the external source"""
+
+    # Get build directory and write CMakeLists.txt file
+    openmc_dir = Path(str(request.config.rootdir)) / 'build'
+    with open('CMakeLists.txt', 'w') as f:
+        f.write(textwrap.dedent("""
+            cmake_minimum_required(VERSION 3.3 FATAL_ERROR)
+            project(openmc_cpp_driver CXX)
+            add_executable(cpp_driver driver.cpp)
+            find_package(OpenMC REQUIRED HINTS {})
+            target_link_libraries(cpp_driver OpenMC::libopenmc)
+            """.format(openmc_dir)))
+
+    # Create temporary build directory and change to there
+    local_builddir = Path('build')
+    local_builddir.mkdir(exist_ok=True)
+    os.chdir(str(local_builddir))
+
+    # Run cmake/make to build the shared libary
+    subprocess.run(['cmake', os.path.pardir], check=True)
+    subprocess.run(['make'], check=True)
+    os.chdir(os.path.pardir)
+
+    yield "./build/cpp_driver"
+
+    # Remove local build directory when test is complete
+    shutil.rmtree('build')
+
+
+@pytest.fixture
+def model():
+    model = openmc.examples.pwr_pin_cell()
+    model.settings.particles = 100
+    model.settings.batches = 10
+    model.settings.inactive = 1
+    return model
+
+class ExternalDriverTestHarness(PyAPITestHarness):
+
+    def __init__(self, executable, statepoint_name, model=None, inputs_true=None):
+        super().__init__(statepoint_name, model, inputs_true)
+        self.executable = executable
+
+    def _run_openmc(self):
+        print("Running openmc")
+        openmc.run(openmc_exec=self.executable)
+
+
+def test_cpp_driver(driver, model):
+    harness = ExternalDriverTestHarness(driver, 'statepoint.10.h5', model, 'inputs_true1.dat')
+    harness.main()
+
+def test_openmc_run(driver, model):
+    # modify model and test again using the openmc exe
+    cell_filter = openmc.CellFilter(list(model.geometry.get_all_cells().values()))
+    tally = openmc.Tally()
+    tally.filters = [cell_filter]
+    tally.scores = ['flux']
+    model.tallies = [tally]
+    harness = PyAPITestHarness('statepoint.10.h5', model, 'inputs_true2.dat')
+    harness.main()