In the previous chapters, we implemented different parts of our app using TDD. Now, it is time to put all the parts together to develop a complete app.

This part of the implementation using TDD is the most exciting one. Usually, when not using TDD, you build and run the app in the simulator all the time to check whether your code works and changes bring the app closer to its final state.

In TDD, most of the development is done without running the app on the simulator or device. The tests guide the implementation. This has one big advantage: you can implement parts of the app that need to talk to a component that has not been implemented yet. For example, you can write and verify the complete data model before a view controller or view is able to show the data on the screen.

In this chapter, we will put the different parts of our code together to form the final app. In addition to this, we will take a look at how functional tests can help to find bugs we missed when writing the unit tests.

This chapter covers the following topics:

• Connecting parts
• Serialization and deserialization
• Functional tests