The Art of Unit Testing

Chapter 4. Interaction testing using mock objects

This chapter covers

• Defining interaction testing
• Understanding mock objects
• Differentiating mocks and stubs
• Exploring mock object best practices

In the previous chapter, we solved the problem of testing code that depends on other objects to run correctly. We used stubs to make sure that the code under test received all the inputs it needed so that we could test its logic independently.

In this chapter, we’ll look at how you test whether an object calls other objects correctly. The object being called may not return any result or save any state, but it has complex logic that needs to result in correct calls to other objects. Using the approach we’ve employed so far won’t do here, because there’s ...