def METHOD_NAME(cli, project, ext):
    cli.add_project(project.dir, as_lppz=project.is_lppz)
    fp_top = project.output_dir + '/top.' + ext
    fp_bot = project.output_dir + '/bot.' + ext
    code, stdout, stderr = cli.run('open-project',
                                   '--export-pnp-top=' + fp_top,
                                   '--export-pnp-bottom=' + fp_bot,
                                   project.path)
    assert stderr == \
        "ERROR: The file '{project.output_dir_native}//bot.{ext}' was " \
        "written multiple times!\n" \
        "ERROR: The file '{project.output_dir_native}//top.{ext}' was " \
        "written multiple times!\n" \
        "NOTE: To avoid writing files multiple times, make sure to pass " \
        "unique filepaths to all export functions. For board output files, " \
        "you could either add the placeholder '{{{{BOARD}}}}' to the path or " \
        "specify the boards to export with the '--board' argument.\n" \
        .format(project=project, ext=ext).replace('//', os.sep)
    assert stdout == \
        "Open project '{project.path}'...\n" \
        "Export top assembly data to '{project.output_dir}/top.{ext}'...\n" \
        "  - 'default' => '{project.output_dir_native}//top.{ext}'\n" \
        "  - 'copy' => '{project.output_dir_native}//top.{ext}'\n" \
        "Export bottom assembly data to '{project.output_dir}/bot.{ext}'...\n" \
        "  - 'default' => '{project.output_dir_native}//bot.{ext}'\n" \
        "  - 'copy' => '{project.output_dir_native}//bot.{ext}'\n" \
        "Finished with errors!\n" \
        .format(project=project, ext=ext).replace('//', os.sep)
    assert code == 1