断言在Python单元测试中调用了方法

我用 Mock (现在) unittest.mock 在PY3.3+上)为此:

from mock import patch
from PyQt4 import Qt


@patch.object(Qt.QMessageBox, 'aboutQt')
def testShowAboutQt(self, mock):
    self.win.actionAboutQt.trigger()
    self.assertTrue(mock.called)

对于您的案例,可能如下所示:

import mock
from mock import patch


def testClearWasCalled(self):
   aw = aps.Request("nv1")
   with patch.object(aw, 'Clear') as mock:
       aw2 = aps.Request("nv2", aw)

   mock.assert_called_with(42) # or mock.assert_called_once_with(42)

mock支持许多有用的特性,包括修补对象或模块的方法,以及检查是否调用了正确的东西等等。

Caveat emptor! (买主当心!)

如果你误入歧途 assert_called_with (到) assert_called_once 或 assert_called_wiht )您的测试可能仍然在运行,因为mock会认为这是一个mocked函数,并且很高兴地继续进行,除非您使用 autospec=true . 欲了解更多信息,请阅读 assert_called_once: Threat or Menace .

是的,如果您使用的是python 3.3+。您可以使用内置的 unittest.mock 调用了断言方法。对于python 2.6+,使用滚动后端端口 Mock 是一样的。

下面是一个简单的例子:

from unittest.mock import MagicMock
aw = aps.Request("nv1")
aw.Clear = MagicMock()
aw2 = aps.Request("nv2", aw)
assert aw.Clear.called

我不知道有什么内置的。实现起来非常简单:

class assertMethodIsCalled(object):
    def __init__(self, obj, method):
        self.obj = obj
        self.method = method

    def called(self, *args, **kwargs):
        self.method_called = True
        self.orig_method(*args, **kwargs)

    def __enter__(self):
        self.orig_method = getattr(self.obj, self.method)
        setattr(self.obj, self.method, self.called)
        self.method_called = False

    def __exit__(self, exc_type, exc_value, traceback):
        assert getattr(self.obj, self.method) == self.called,
            "method %s was modified during assertMethodIsCalled" % self.method

        setattr(self.obj, self.method, self.orig_method)

        # If an exception was thrown within the block, we've already failed.
        if traceback is None:
            assert self.method_called,
                "method %s of %s was not called" % (self.method, self.obj)

class test(object):
    def a(self):
        print "test"
    def b(self):
        self.a()

obj = test()
with assertMethodIsCalled(obj, "a"):
    obj.b()

这要求对象本身不会修改self.b,这几乎总是正确的。

是的,我可以给你提纲,但我的蟒蛇有点生锈,我太忙了,无法详细解释。

基本上,您需要在调用原始对象的方法中放置一个代理,例如:

 class fred(object):
   def blog(self):
     print "We Blog"


 class methCallLogger(object):
   def __init__(self, meth):
     self.meth = meth

   def __call__(self, code=None):
     self.meth()
     # would also log the fact that it invoked the method

 #example
 f = fred()
 f.blog = methCallLogger(f.blog)

这个 StackOverflow answer 关于Callable可以帮助您理解上面的内容。

更详细地说:

尽管答案被接受了,但由于与格伦的讨论很有趣,并且有几分钟的空闲时间,我想进一步讨论我的答案:

# helper class defined elsewhere
class methCallLogger(object):
   def __init__(self, meth):
     self.meth = meth
     self.was_called = False

   def __call__(self, code=None):
     self.meth()
     self.was_called = True

#example
class fred(object):
   def blog(self):
     print "We Blog"

f = fred()
g = fred()
f.blog = methCallLogger(f.blog)
g.blog = methCallLogger(g.blog)
f.blog()
assert(f.blog.was_called)
assert(not g.blog.was_called)

你可以模仿 aw.Clear 手动或使用类似的测试框架 pymox . 手动操作时,您可以使用如下方法:

class MyTest(TestCase):
  def testClear():
    old_clear = aw.Clear
    clear_calls = 0
    aw.Clear = lambda: clear_calls += 1
    aps.Request('nv2', aw)
    assert clear_calls == 1
    aw.Clear = old_clear

使用Pymox,你可以这样做:

class MyTest(mox.MoxTestBase):
  def testClear():
    aw = self.m.CreateMock(aps.Request)
    aw.Clear()
    self.mox.ReplayAll()
    aps.Request('nv2', aw)