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)

Testing actors

Actor-based systems are different from systems that are built using a traditional approach. Naturally, testing actors is different from regular testing. Actors send and receive messages in an asynchronous manner and are usually examined via message flow analysis. A typical setup will include three parts:

  1. The source of the messages
  2. The actor under test
  3. The receiver of the actor's responses

Luckily, Akka includes a testing module that abstracts a lot of setup logic and provides useful helpers for common testing activities. The name of the module is Akka TestKit and it is contained in a separate module that needs to be added to the project's test scope:

libraryDependencies += "com.typesafe.akka" %% "akka-testkit" % akkaVersion % Test

Having this dependency allows us to extend a TestKit class. The TestKit implements a special testing...