python - Pytest:模拟/猴子修补 python 中的内置 input() 和 print() 函数

Question

我如何使用 Pytest 猴子修补内置的 input 和 print 函数，以便捕获其他人代码的输出并使用 pytest 重构之前？

例如，我获得了一些类似这样的代码:

class QueryProcessor:
    def __init__(self ...):
        ...  

    def write_search_result(self, was_found):
        print('yes' if was_found else 'no')

    def read_query(self):
        return Query(input().split())

我不想从 stdin 读取几十个输入参数，也不想打印 输出。我想使用我编写的函数筛选一个充满 mytest.in 和 mytest.out 文件的目录，并将输入传递给 pytest 使用 @pytest.mark.parametrize(...)。

但是我不知道如何修补这个类中笨拙的read... 和write... 函数。

我怀疑是这样的:

@yptest.mark.parametrize("inputs…, expected outputs…", data_reading_func())
def test_QueryProcessor(monkeypatch, inputs…, expected outputs…):
   """Docstring
   """
   q = QueryProcessor()

   def my_replacement_read():
       ...
       return [...]

   def my_replacement_write():
       ...
       return [...]

   monkeypatch.???
   assert ...

你能帮忙吗？

非常感谢

Answer 1

在等待回复的过程中，我自己想到了以下内容。我认为理想的答案是我按照@hoefling 所建议的方式实现的——使用patch。

@pytest.mark.parametrize("m, n, commands, expec", helpers.get_external_inputs_outputs('spampath', helpers.read_spam_input_output))
def test_QueryProcessor(monkeypatch, m, n, commands, expec):

    def mock_process_queries(cls):
        for cmd in commands:
            cls.process_query(Query(cmd.split())) # also mocks read_query()

    def mock_write_search_result(cls, was_found):
        outputs.append('yes' if was_found else 'no')

    monkeypatch.setattr('test.QueryProcessor.process_queries', mock_process_queries)
    monkeypatch.setattr('test.QueryProcessor.write_search_result', mock_write_search_result)

    outputs = []

    proc = QueryProcessor(m)
    proc.process_queries()

    assert outputs == expec

更新:

@pytest.mark.parametrize("m, n, commands, expec",
                         helpers.get_external_inputs_outputs(
                             'spampath',
                             helpers.read_input_output))
def test_QueryProcessor_mockpatch(m, n, commands, expec):

    commands.insert(0,n)

    mock_stdout = io.StringIO()

    with patch('spammodule.input', side_effect=commands):
        with patch('sys.stdout', mock_stdout):
            proc = hash_chains.QueryProcessor(m)
            proc.process_queries()

    assert mock_stdout.getvalue().split('\n')[:-1] == expec