Book Image

Learn Scala Programming

By : Slava Schmidt
Book Image

Learn Scala Programming

By: Slava Schmidt

Overview of this book

The second version of Scala has undergone multiple changes to support features and library implementations. Scala 2.13, with its main focus on modularizing the standard library and simplifying collections, brings with it a host of updates. Learn Scala Programming addresses both technical and architectural changes to the redesigned standard library and collections, along with covering in-depth type systems and first-level support for functions. You will discover how to leverage implicits as a primary mechanism for building type classes and look at different ways to test Scala code. You will also learn about abstract building blocks used in functional programming, giving you sufficient understanding to pick and use any existing functional programming library out there. In the concluding chapters, you will explore reactive programming by covering the Akka framework and reactive streams. By the end of this book, you will have built microservices and learned to implement them with the Scala and Lagom framework.
Table of Contents (19 chapters)


Currently, we have a working Bakery implementation, but we cannot be sure that our actors are doing what we expect them to do. Let's fix this by testing their behavior.

Testing actors is notoriously difficult because of their concurrent nature and message orientation. Luckily, in Akka Typed, an actor's behavior is just a function and thus can generally be tested in isolation. There are cases where we might want to test the interaction between actors, and in this case, it is inevitable to resort to asynchronous testing.

In synchronous setup, we create a behavior under test, send events that it should be able to react on, and verify that the behavior produces the expected effects (for example, spawning or stopping child actors) and sends further required messages.

The asynchronous scenario brings this approach into the context of a test actor system, which is close...