We've covered a lot of territory in this chapter, looking at three distinct areas of testing: unit testing, REST API testing, and UI functional tests. Ensuring that an application is well tested is an important step on the road to software success. A team that does not follow good testing practices is often bogged down with fixing regression after regression.

We've talked about the potential simplicity of simply using the assert module for testing. While the test frameworks, such as Mocha, provide great features, we can go a long way with a simple script.

There is a place for test frameworks, such as Mocha, if only to regularize our test cases, and to produce test results reports. We used Mocha and Chai for this, and these tools were quite successful. We even found a couple of bugs with a small test suite.

When starting down the unit testing road, one design consideration is mocking out dependencies. But it's not always a good use of our time to replace every dependency with a mock version.

To ease the administrative burden of running tests, we used Docker to automate setting up and tearing down the test infrastructure. Just as Docker was useful in automating deployment of the Notes application, it's also useful in automating test infrastructure deployment.

Finally, we were able to test the Notes web user interface in a real web browser. We can't trust that unit testing will find every bug; some bugs will only show up in the web browser. Even so, we've only touched the beginning of what could be tested in Notes.

In this book, we've covered the gamut of Node.js development, giving you a strong foundation from which to start developing Node.js applications.

In the next chapter, we'll explore RESTful web services.