Question

使用open()库来模拟和测试mock返回的对象的代码是正确的？

whitelist_data.py：

WHITELIST_FILE = "testdata.txt"

format_str = lambda s: s.rstrip().lstrip('www.')
whitelist = None

with open(WHITELIST_FILE) as whitelist_data:
    whitelist = set(format_str(line) for line in whitelist_data)

if not whitelist:
    raise RuntimeError("Can't read data from %s file" % WHITELIST_FILE)

def is_whitelisted(substr):
    return 1 if format_str(substr) in whitelist else 0

以下是我尝试测试它的方法。

import unittest
import mock 

TEST_DATA = """
domain1.com
domain2.com
domain3.com
"""

class TestCheckerFunctions(unittest.TestCase):

    def test_is_whitelisted_method(self):
        open_mock = mock.MagicMock()
        with mock.patch('__builtin__.open',open_mock):
            manager = open_mock.return_value.__enter__.return_value
            manager.__iter__ = lambda s: iter(TEST_DATA.splitlines())
            from whitelist_data import is_whitelisted
            self.assertTrue(is_whitelisted('domain1.com'))

if __name__ == '__main__':
    unittest.main()

python tests.py的结果是：

$ python tests.py

E
======================================================================
ERROR: test_is_whitelisted_method (__main__.TestCheckerFunctions)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "tests.py", line 39, in test_is_whitelisted_method
    from whitelist_data import is_whitelisted
  File "/Users/supa/Devel/python/whitelist/whitelist_data.py", line 20, in <module>
    whitelist = set(format_str(line) for line in whitelist_data)
TypeError: 'Mock' object is not iterable

----------------------------------------------------------------------
Ran 1 test in 0.001s

UPD：感谢Adam，我重新安装了模拟库（pip install -e hg+https://code.google.com/p/mock#egg=mock）并更新了tests.py.像魅力一样。

Answer 1

您正在寻找MagicMock。这支持迭代。

在模拟0.80beta4中，patch返回MagicMock。所以这个简单的例子有效：

import mock

def foo():
    for line in open('myfile'):
        print line

@mock.patch('__builtin__.open')
def test_foo(open_mock):
    foo()
    assert open_mock.called

如果你正在运行模拟0.7.x（它看起来像你），我认为你不能单独使用补丁来实现这一点。您需要单独创建模拟，然后将其传递给补丁：

import mock

def foo():
    for line in open('myfile'):
        print line

def test_foo():
    open_mock = mock.MagicMock()
    with mock.patch('__builtin__.open', open_mock):
        foo()
        assert open_mock.called

注意 - 我用py.test运行这些，但是，这些相同的方法也适用于unittest。

在python中模拟文件对象或迭代

1 个答案: