Question

如何使用Pytest对内置input和print函数进行修补，以便在重构之前捕获其他人的代码输出并使用pytest进行测试？

例如，我已经获得了类似的代码：

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读取数十个输入参数，我也不想print输出。我想使用我编写的函数来筛选一个充满mytest.in和mytest.out文件的目录，并使用pytest将输入传递给@pytest.mark.parametrize(...)。

但我无法弄清楚如何修补此类中笨拙的read…和write…函数。

我怀疑它的含义如下：

@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

在等待回复的同时，我自己想出了以下内容。我认为理想的答案将是我用@hoefling建议使用patch的方式实现的。

@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

Answer 2

嘿，我想这对你来说太晚了，但对于其他人问自己如何使用monkeypatch input()，我是这样做的：

monkeypatch.setattr(builtins, 'input', lambda *args, **kwargs: 'Yes, I like monkeypatching')

因此，我会重构您在自己的答案中发布的代码，并将其更新为（假设命令是可调用的，因为您将其指定为 side_effect）：

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

    commands.insert(0,n)

    mock_stdout = io.StringIO()
    monkeypatch.setattr(builtins, 'input', lambda description: commands())
    monkeypatch.setattr(sys, 'stdout', mock_stdout)

    proc = hash_chains.QueryProcessor(m)
    proc.process_queries()

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

Pytest：在python中

2 个答案: