Automated software testing predates the history of DevOps, but it is a good starting point. Too often, developers focus on implementing features and forget to add a test to their code. In a DevOps environment, developers are responsible for adding proper testing to their code. QA teams can still exist; however, similar to other engineering teams, they work on building automation around testing.

This topic could deserve its own book, but in a nutshell, when developing code, keep in mind that there are four levels of testing automation to focus on to successfully implement DevOps:

• Unit test: This is to test the functionality of each code block and function.
• Integration testing: This is to make sure that services and components work together.
• User interface testing: This is often the most challenging one to implement successfully.
• System testing: This is end-to-end testing. Let's take an example of a photo-sharing application. Here, the end-to-end testing could involve opening the homepage, signing in, uploading a photo, adding a caption, publishing the photo, and then signing out.