Book Image

Reactive Programming in Kotlin

By : Rivu Chakraborty
Book Image

Reactive Programming in Kotlin

By: Rivu Chakraborty

Overview of this book

In today's app-driven era, when programs are asynchronous, and responsiveness is so vital, reactive programming can help you write code that's more reliable, easier to scale, and better-performing. Reactive programming is revolutionary. With this practical book, Kotlin developers will first learn how to view problems in the reactive way, and then build programs that leverage the best features of this exciting new programming paradigm. You will begin with the general concepts of Reactive programming and then gradually move on to working with asynchronous data streams. You will dive into advanced techniques such as manipulating time in data-flow, customizing operators and provider and how to use the concurrency model to control asynchronicity of code and process event handlers effectively. You will then be introduced to functional reactive programming and will learn to apply FRP in practical use cases in Kotlin. This book will also take you one step forward by introducing you to Spring 5 and Spring Boot 2 using Kotlin. By the end of the book, you will be able to build real-world applications with reactive user interfaces as well as you'll learn to implement reactive programming paradigms in Android.
Table of Contents (20 chapters)
Title Page
About the Author
About the Reviewers
Customer Feedback

Introducing TestObserver and TestSubscriber

As you read through this chapter, you may have developed an idea that the only way we can perform tests are through blocking the code, either by using blockingSubscribe or by using blocking operators. But this is not the case. In fact, there are more comprehensive ways to reactive code, or rather we can say that we can test reactive code reactively.

To say it more precisely, in a Subscriber we have onError and onComplete that demands testing along with onNext, which is not always possible with just blocking. Yes some sort of blocking is necessary, but it cannot alone do all the things and it also needs to be managed reactively.

So, here are your two superheroes to make the developers life easy—TestObserver and TestSubscriber. As with Subscriber and Observer, you can use TestSubscriber with Flowables and TestObserver with Observables, everything except that is similar between these two.

So, let's get started with an example:

    fun `test...