def generate_test_numbers(test_class):
    counter = 1
    for method_name in dir(test_class):
        if not method_name.startswith('test_N_'):
            continue
        method = getattr(test_class, method_name)
        if not callable(method):
            continue
        new_method_name = method_name.replace('_N_', '_{:02d}_'.format(counter))
        counter += 1
        setattr(test_class, new_method_name, method)
        delattr(test_class, method_name)
    return test_class