我读过各种关于测试中模仿和存根的文章,包括Martin Fowler的《Mocks Aren't Stubs》,但我仍然不理解其中的区别。
当前回答
下面是对每一个的描述,然后是真实世界的样本。
Dummy - just bogus values to satisfy the API. Example: If you're testing a method of a class which requires many mandatory parameters in a constructor which have no effect on your test, then you may create dummy objects for the purpose of creating new instances of a class. Fake - create a test implementation of a class which may have a dependency on some external infrastructure. (It's good practice that your unit test does NOT actually interact with external infrastructure.) Example: Create fake implementation for accessing a database, replace it with in-memory collection. Stub - override methods to return hard-coded values, also referred to as state-based. Example: Your test class depends on a method Calculate() taking 5 minutes to complete. Rather than wait for 5 minutes you can replace its real implementation with stub that returns hard-coded values; taking only a small fraction of the time. Mock - very similar to Stub but interaction-based rather than state-based. This means you don't expect from Mock to return some value, but to assume that specific order of method calls are made. Example: You're testing a user registration class. After calling Save, it should call SendConfirmationEmail.
存根和Mock实际上是Mock的子类型,两者都交换了实际实现和测试实现,但出于不同的、特定的原因。
其他回答
测试双打:
Fake: Fakes are objects that have working implementations, but not the same as production one. Such as: in-memory implementation of Data Access Object or Repository. Stub: Stub is an object that holds predefined data and uses it to answer calls during tests. Such as: an object that needs to grab some data from the database to respond to a method call. Mocks: Mocks are objects that register calls they receive. In test assertion, we can verify on Mocks that all expected actions were performed. Such as: a functionality that calls e-mail sending service. for more just check this.
Stub
我相信最大的区别是您已经编写了带有预定行为的存根。所以你会有一个实现依赖的类(很可能是抽象类或接口),你是为了测试目的而伪造的,方法只是用设置的响应来存根。它们不会做任何花哨的事情,而且您应该已经在测试之外为它编写了存根代码。
Mock
模拟是测试的一部分,你必须根据你的期望来设置。mock并不是预先设定好的,所以您可以在测试中使用它。模拟在某种程度上是在运行时确定的,因为设置期望的代码必须在它们执行任何操作之前运行。
mock和stub的区别
使用模拟编写的测试通常遵循初始化->设置期望->练习->验证模式进行测试。而预先编写的存根将遵循初始化->练习->验证。
mock和stub之间的相似性
这两种方法的目的都是为了消除对类或函数的所有依赖项的测试,从而使您的测试在试图证明的内容方面更加集中和简单。
存根是一个简单的伪对象。它只是确保测试顺利进行。 mock是更聪明的存根。您验证您的测试通过了它。
存根和模拟都覆盖外部依赖项,但区别在于
stub ->用于测试数据
mock ->用于测试行为
不测试任何东西(只是用空方法覆盖功能,例如替换Logger以避免在测试时记录任何噪音)
我偶然看到了《小嘲笑者鲍勃叔叔》的一篇有趣的文章。它以一种非常容易理解的方式解释了所有的术语,因此对初学者很有用。Martin fowler的文章很难读,尤其是对于像我这样的初学者。
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