如何使用pytest monkeypatch模拟两个连续的控制台输入

Question

如果第一个用户输入用“ n”回答，则模块“ overwrite_file”（请参见代码示例）要求输入新文件名。

在我的测试设置中，我使用两个连续的monkeypatch.setattr调用来模拟输入。如果我使用以下顺序，结果将是一个无限循环：

monkeypatch.setattr('builtins.input', lambda overwrite: "n")
monkeypatch.setattr('builtins.input', lambda new_name: new_filename)
已激活第二个Monkeypatch.setattr调用，并将'new.pkl'分配给变量覆盖。 

如果我这样更改monkeypatch命令的顺序：

monkeypatch.setattr('builtins.input', lambda new_name: new_filename)
monkeypatch.setattr('builtins.input', lambda overwrite: "n")
我收到一个AssertionError，因为将'n'分配给变量new_name并创建了一个名为“ n”的文件。

我如何获得预期的测试功能？

解释器：Python 3.8

from os.path import exists, join, dirname
import pickle
import pytest


def overwrite_file(filename):
    # loop until overwrite existing file or input of a file name which does not exist
    dump_file = False
    while not dump_file:
        if exists(filename):
            overwrite = input(f"overwrite {filename} (y/n): ")
            if overwrite in ["y", "Y"]:
                dump_file = True
            if overwrite in ["n", "N"]:
                new_name = input("new filename: ")
                filename = join(dirname(filename), new_name)
        else:
            dump_file = True

    return filename


@pytest.fixture()
def pickle_test_env(tmpdir_factory):
    a_dir = tmpdir_factory.mktemp('src_dir')
    a_file = a_dir.join('already_there.pkl')
    with open(a_file, "wb") as f:
        pickle.dump({"C": 27.1, "S": -8.2, "T": 29.7}, f)
    return a_dir


def test_new_filename_if_file_exists(pickle_test_env, monkeypatch):
    """ is overwrite_file returning a valid new filename if filename exists
    and should not be overwritten? """
    filename = 'already_there.pkl'
    new_filename = 'new.pkl'
    assert exists(join(pickle_test_env, filename))
    monkeypatch.setattr('builtins.input', lambda new_name: new_filename)
    monkeypatch.setattr('builtins.input', lambda overwrite: "n")
    assert overwrite_file(join(pickle_test_env, filename)) == join(pickle_test_env, new_filename)

如果第一个用户输入用“ n”回答，则模块“ overwrite_file”（请参见代码示例）要求输入新文件名。在我的测试设置中，我使用了两个连续的monkeypatch.setattr调用，以...

Answer 1

[最后一个猴子补丁将击败其他所有猴子，所以input(f"overwrite {filename} (y/n): ")得到"n"，input("new filename: ")也得到。为了以正确的顺序提供所需的输入，我们可以对方法进行循环修改，以循环响应]