In this chapter, we've learned about a family of objects that specialize in impersonating other classes, objects, methods, and functions. We've seen how to configure these objects to handle corner cases where their default behavior isn't sufficient, and we've learned how to examine the activity logs that these mock objects keep, so that we can decide whether the objects are being used properly or not.

In the next chapter, we'll look at Python's unittest package, a more structured testing framework that is less useful for communicating with people than doctest is, but better able to handle the complexities of large-scale testing.