In this chapter, we covered two important aspects of Java programming that play a significant role in most real-world Java applications--build systems and testing. We looked at how we can use Maven to structure our projects and align Maven's multi-module project concepts with Java 9 modular applications. We examined how such an application looks like, and learned how to compile and execute the application through Maven lifecycle processes. We then learned about how testing can be incorporated into a Java modular application. We looked at some of the challenges with testing that result from some constraints that Java modularity introduces to the language and how to work around them. We then created a JUnit test case and leveraged the JUnit framework to execute a module test case.