def METHOD_NAME(request, tmpdir):
    """
    Fixture that prepares a simulation directory with a completed 50-iteration WESTPA,
    west.h5, plus the config file west.cfg
    """
    test_dir = str(tmpdir)
    os.chdir(test_dir)
    copy_ref(test_dir)
    copyfile(os.path.join(REFERENCE_PATH, 'west_ref.h5'), H5_FILENAME)
    copyfile(os.path.join(REFERENCE_PATH, 'west_ref.cfg'), CFG_FILENAME)
    request.cls.cfg_filepath = CFG_FILENAME
    request.cls.h5_filepath = H5_FILENAME
    os.environ['WEST_SIM_ROOT'] = test_dir
    westpa.rc = westpa.core._rc.WESTRC()
    request.addfinalizer(clear_state)