A fake is a generic term that can be used to describe either a stub or a mock object (handwritten or otherwise), because they both look like the real object. Whether a fake is a stub or a mock depends on how it’s used in the current test. If it’s used to check an interaction (asserted against), it’s a mock object. Otherwise, it’s a stub. Fakes makes sure test runs smoothly. It means that reader of your future test will understand what will be the behavior of the fake object, without needing to read its source code (without needing to depend on external resource). What does test run smoothly mean? Forexample in below code: public void Analyze(string filename) { if(filename.Length<8) { try { errorService.LogError("long file entered named:" + filename); } catch (Exception e) { mailService.SendEMail("admin@hotmail.com", "ErrorOnWebService", "someerror"); } } } You want to test mailService.SendEMail() method, to do that you need to simulate an Exception in you test method, so you just need to create a Fake Stub errorService class to simulate that result, then your test code will be able to test mailService.SendEMail() method. As you see you need to simulate a result which is from an another External Dependency ErrorService class.

存根用于您在测试中设置的具有预期返回值的方法。 mock用于void方法，这些方法在调用时的Assert中进行验证。

在codeschool.com的课程《Rails僵尸测试》中，他们给出了这些术语的定义:

Stub

用于将方法替换为返回指定结果的代码。

Mock

带有调用方法的断言的存根。

因此，正如Sean Copenhaver在他的回答中所描述的那样，不同之处在于mock设置了期望(即做出断言，关于是否或如何调用它们)。

看了上面所有的解释，让我试着总结一下:

Stub:让测试运行的一段虚拟代码，但您并不关心它会发生什么。替代实际工作代码。 Mock:在测试中验证是否正确调用的一段虚拟代码。替代实际工作代码。 间谍:一段虚拟代码，用于拦截和验证对实际工作代码的某些调用，从而避免替换所有实际代码。

在我的回答中，我使用了python示例来说明差异。

Stub - Stubbing is a software development technique used to implement methods of classes early in the development life-cycle. They are used commonly as placeholders for implementation of a known interface, where the interface is finalized or known but the implementation is not yet known or finalized. You begin with stubs, which simply means that you only write the definition of a function down and leave the actual code for later. The advantage is that you won't forget methods and you can continue to think about your design while seeing it in code. You can also have your stub return a static response so that the response can be used by other parts of your code immediately. Stub objects provide a valid response, but it's static no matter what input you pass in, you'll always get the same response:

class Foo(object):
    def bar1(self):
        pass

    def bar2(self):
        #or ...
        raise NotImplementedError

    def bar3(self):
        #or return dummy data
        return "Dummy Data"

模拟对象用于模拟测试用例，它们验证在这些对象上调用了某些方法。模拟对象是以可控的方式模拟真实对象行为的模拟对象。您通常创建一个模拟对象来测试其他对象的行为。mock让我们模拟对于单元测试来说不可用或太笨重的资源。

mymodule.py:

import os
import os.path

def rm(filename):
    if os.path.isfile(filename):
        os.remove(filename)

test.py:

from mymodule import rm
import mock
import unittest

class RmTestCase(unittest.TestCase):
    @mock.patch('mymodule.os')
    def test_rm(self, mock_os):
        rm("any path")
        # test that rm called os.remove with the right parameters
        mock_os.remove.assert_called_with("any path")

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

这是一个非常基本的示例，它只运行rm并断言调用它的参数。您可以对对象使用mock，而不仅仅是这里所示的函数，您还可以返回一个值，这样模拟对象就可以用来替换存根进行测试。

更多关于unittest的信息。模拟，注意python 2。X mock不包含在unittest中，但它是一个可下载的模块，可以通过PIP (PIP install mock)下载。

我还读过Roy Osherove写的《单元测试的艺术》，我认为如果有一本类似的书是用Python和Python示例编写的，那就太棒了。如果有人知道这样的书，请分享。欢呼:)

我在阅读《单元测试的艺术》时，偶然发现了以下定义:

fake是一个通用术语，可以用来描述存根或模拟对象(手写或其他)，因为它们看起来都像真实的对象。赝品是存根还是mock取决于它在当前测试中的使用方式。如果它用于检查交互(根据其断言)，则它是一个模拟对象。否则，它就是存根。