Book Image

Learning RxJava

By : Thomas Nield
Book Image

Learning RxJava

By: Thomas Nield

Overview of this book

RxJava is a library for composing asynchronous and event-based programs using Observable sequences for the JVM, allowing developers to build robust applications in less time. Learning RxJava addresses all the fundamentals of reactive programming to help readers write reactive code, as well as teach them an effective approach to designing and implementing reactive libraries and applications. Starting with a brief introduction to reactive programming concepts, there is an overview of Observables and Observers, the core components of RxJava, and how to combine different streams of data and events together. You will also learn simpler ways to achieve concurrency and remain highly performant, with no need for synchronization. Later on, we will leverage backpressure and other strategies to cope with rapidly-producing sources to prevent bottlenecks in your application. After covering custom operators, testing, and debugging, the book dives into hands-on examples using RxJava on Android as well as Kotlin.
Table of Contents (21 chapters)
Title Page
Credits
About the Author
Acknowledgements
About the Reviewers
www.PacktPub.com
Customer Feedback
Preface

Using TestObserver and TestSubscriber


We've covered blockingSubscribe() and several blocking operators in this chapter so far. While you can use these blocking tools to do simple assertions, there is a much more comprehensive way to test reactive code than simply blocking for one or more values. After all, we should do more than test onNext() calls. We also have onComplete() and onError() events to account for! It also would be great to streamline testing other RxJava events, such as subscription, disposal, and cancellation.

So let's introduce the TestObserver and TestSubscriber, your two best friends in testing your RxJava applications.

TestObserver and TestSubscriber are a treasure trove of convenient methods to aid testing, many of which assert that certain events have occurred or specific values were received. There are also blocking methods, such as awaitTerminalEvent(), which will stop the calling thread until the reactive operation terminates.

TestObserver is used for Observable, Single...