13

哪种方式适合使用模拟库来模拟和测试由open()返回的 iters 对象的代码？

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

这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()

结果python tests.py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 mock library( pip install -e hg+https://code.google.com/p/mock#egg=mock) 并更新了 tests.py。奇迹般有效。

4

1 回答 1

16

您正在寻找一个MagicMock. 这支持迭代。

在模拟 0.80beta4 中，patch返回一个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

如果您正在运行模拟 0.7.x（看起来您是），我认为您无法单独使用补丁来完成此操作。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

Note - I've run these with py.test, however, these same approaches will work with unittest as well.

于 2011-11-17T14:27:55.177 回答