Testing Elixir

Property-based testing helps you create better, more solid tests with little code. By using the PropEr framework in both Erlang and Elixir, this book teaches you how to automatically generate test cases, test stateful programs, and change how you design your software for more principled and reliable approaches. You will be able to better explore the problem space, validate the assumptions you make when coming up with program behavior, and expose unexpected weaknesses in your design. PropEr will even show you how to reproduce the bugs it found. With this book, you will be writing efficient property-based tests in no time. Most tests only demonstrate that the code behaves how the developer expected it to behave, and therefore carry the same blind spots as their authors when special conditions or edge cases show up. Learn how to see things differently with property tests written in PropEr. Start with the basics of property tests, such as writing stateless properties, and using the default generators to generate test cases automatically. More importantly, learn how to think in properties. Improve your properties, write custom data generators, and discover what your code can or cannot do. Learn when to use property tests and when to stick with example tests with real-world sample projects. Explore various testing approaches to find the one that's best for your code. Shrink failing test cases to their simpler expression to highlight exactly what breaks in your code, and generate highly relevant data through targeted properties. Uncover the trickiest bugs you can think of with nearly no code at all with two special types of properties based on state transitions and finite state machines. Write Erlang and Elixir properties that generate the most effective tests you'll see, whether they are unit tests or complex integration and system tests. What You Need Basic knowledge of Erlang, optionally ElixirFor Erlang tests: Erlang/OTP >= 20.0, with Rebar >= 3.4.0For Elixir tests: Erlang/OTP >= 20.0, Elixir >= 1.5.0

Elixir offers new paradigms, and challenges you to test in unconventional ways. Start with ExUnit: almost everything you need to write tests covering all levels of detail, from unit to integration, but only if you know how to use it to the fullest - we'll show you how. Explore testing Elixir-specific challenges such as OTP-based modules, asynchronous code, Ecto-based applications, and Phoenix applications. Explore new tools like Mox for mocks and StreamData for property-based testing. Armed with this knowledge, you can create test suites that add value to your production cycle and guard you from regressions. Write Elixir tests that you can be proud of. Dive into Elixir's test philosophy and gain mastery over the terminology and concepts that underlie good tests. Create and structure a comprehensive ExUnit test suite, starting from the basics, and build comprehensive test coverage that will provide safety for refactoring and confidence that your code performs as designed. Use tests to make your software more reliable and fault tolerant. Explore the basic tool set provided by ExUnit and Mix to write and organize your test suite. Test code built around different OTP functionality. Isolate your code through dependency injection and by using Mox. Write comprehensive tests for Ecto projects, covering Ecto as a database tool as well as a standalone data validation tool. Test Phoenix channels from end to end, including authentication and joining topics. Write Phoenix controller tests and understand the concepts of integration testing in Elixir. Learn property-based testing with StreamData from the author who wrote the library. Code with high confidence that you are getting the most out of your test suite, with the right tools that make testing your code a pleasure and a valuable part of your development cycle. What You Need: To get the most out of this book, you will need to have installed Elixir 1.8 or later and Erlang/OTP 21 or later. In order to complete the relevant chapters, you will also need Ecto 3.1 or later, EctoSQL 3.1 or later and Phoenix 1.3 or later.

Don't accept the compromise between fast and beautiful: you can have it all. Phoenix creator Chris McCord, Elixir creator Jose Valim, and award-winning author Bruce Tate walk you through building an application that's fast and reliable. At every step, you'll learn from the Phoenix creators not just what to do, but why. Packed with insider insights, this definitive guide will be your constant companion in your journey from Phoenix novice to expert, as you build the next generation of web applications. Phoenix is the long-awaited web framework based on Elixir, the highly concurrent language that combines a beautiful syntax with rich metaprogramming. The authors, who developed the earliest production Phoenix applications, will show you how to create code that's easier to write, test, understand, and maintain. The best way to learn Phoenix is to code, and you'll get to attack some interesting problems. Start working with controllers, views, and templates within the first few pages. Build an in-memory repository, and then back it with an Ecto database layer. Learn to use change sets and constraints that keep readers informed and your database integrity intact. Craft your own interactive application based on the channels API for the real-time, high-performance applications that this ecosystem made famous. Write your own authentication components called plugs, and even learn to use the OTP layer for monitored, reliable services. Organize your code with umbrella projects so you can keep your applications modular and easy to maintain. This is a book by developers and for developers, and we know how to help you ramp up quickly. Any book can tell you what to do. When you've finished this one, you'll also know why to do it. What You Need: To work through this book, you will need a computer capable of running Erlang 17 or better, Elixir 1.1, or better, Phoenix 1.0 or better, and Ecto 1.0 or better. A rudimentary knowledge of Elixir is also highly recommended.

Elixir will change the way you think about programming. Use your Ruby experience to quickly get up to speed so you can see what all of the buzz is about. Go from zero to production applications that are reliable, fast, and scalable. Learn Elixir syntax and pattern matching to conquer the basics. Then move onto Elixir's unique process model that offers a world-class way to go parallel without fear. Finally, use the most common libraries like Ecto, Phoenix, and Oban to build a real-world SMS application. Now's the time. Dive in and learn Elixir. Whether you're a seasoned Ruby developer looking to expand your skill set or a programming beginner looking for a solid foundation in Elixir, this book has what you need to get up to speed quickly. Elixir is a functional language with a fairly small footprint. This makes it easier to learn and put into production than other languages. Plus, it's built on forty-year-old foundations that give your applications rock-solid stability. The first part of this book is all about developing expertise in the language. Learn about the core data types, build application data structures, enumerate over data, and use pattern matching to control the flow of an application. Elixir has an amazing process model that allows for (actually) easy parallel processing. Learn how to tap into this process model so you can leverage that power yourself. The second part of this book builds a real-world application using the most important libraries in a web developer's toolbox. Each library is compared to its similar Ruby library so you'll quickly see similarities and differences. We'll use Ecto, Phoenix, and Oban to build a SMS application powered by Twilio. What are you waiting for? Tap into your Ruby knowledge and start building scalable Elixir applications today. What You Need: You'll need Elixir 1.14+ and Erlang/OTP 24+ installed on a Mac OS X, Linux, or Windows machine.

Languages may come and go, but the relational database endures. Learn how to use Ecto, the premier database library for Elixir, to connect your Elixir and Phoenix apps to databases. Get a firm handle on Ecto fundamentals with a module-by-module tour of the critical parts of Ecto. Then move on to more advanced topics and advice on best practices with a series of recipes that provide clear, step-by-step instructions on scenarios commonly encountered by app developers. Co-authored by the creator of Ecto, this title provides all the essentials you need to use Ecto effectively. Elixir and Phoenix are taking the application development world by storm, and Ecto, the database library that ships with Phoenix, is going right along with them. There are plenty of examples that show you the basics, but to use Ecto to its full potential, you need to learn the library from the ground up. This definitive guide starts with a tour of the core features of Ecto - repos, queries, schemas, changesets, transactions - gradually building your knowledge with tasks of ever-increasing complexity. Along the way, you'll be learning by doing - a sample application handles all the boilerplate so you can focus on getting Ecto into your fingers. Build on that core knowledge with a series of recipes featuring more advanced topics. Change your pooling strategy to maximize your database's efficiency. Use nested associations to handle complex table relationships. Add streams to handle large result sets with ease. Based on questions from Ecto users, these recipes cover the most common situations developers run into. Whether you're new to Ecto, or already have an app in production, this title will give you a deeper understanding of how Ecto works, and help make your database code cleaner and more efficient. What You Need: To follow along with the book, you should have Erlang/OTP 19+ and Elixir 1.4+ installed. The book will guide you through setting up a sample application that integrates Ecto.

Adoption is more than programming. Elixir is an exciting new language, but to successfully get your application from start to finish, you're going to need to know more than just the language. The case studies and strategies in this book will get you there. Learn the best practices for the whole life of your application, from design and team-building, to managing stakeholders, to deployment and monitoring. Go beyond the syntax and the tools to learn the techniques you need to develop your Elixir application from concept to production. Learn real-life strategies from the people who built Elixir and use it successfully at scale. See how Ben Marx and Bleacher Report maintain one of the highest-traffic Elixir applications by selling the concept to management and delivering on that promise. Find out how Bruce Tate and icanmakeitbetter hire and train Elixir engineers, and the techniques they've employed to design and ensure code consistency since Elixir's early days. Explore customer challenges in deploying and monitoring distributed applications with Elixir creator Jose Valim and Plataformatec. Make a business case and build a team before you finish your first prototype. Once you're in development, form strategies for organizing your code and learning the constraints of the runtime and ecosystem. Convince stakeholders, both business and technical, about the value they can expect. Prepare to make the critical early decisions that will shape your application for years to come. Manage your deployment with all of the knobs and gauges that good DevOps teams demand. Decide between the many options available for deployment, and how to best prepare yourself for the challenges of running a production application. This book picks up where most Elixir books leave off. It won't teach you to program Elixir, or any of its tools. Instead, it guides you through the broader landscape and shows you a holistic approach to adopting the language. What You Need: This book works with any version of Elixir.

Leverage the power of Elixir programming language to solve practical problems associated with scalability, concurrency, fault tolerance, and high availability. Key Features Enhance your Elixir programming skills using its powerful tools and abstractions Discover how to develop a full-fledged file server Understand how to use Phoenix to create a web interface for your application. Book Description Running concurrent, fault-tolerant applications that scale is a very demanding responsibility. After learning the abstractions that Elixir gives us, developers are able to build such applications with inconceivable low effort. There is a big gap between playing around with Elixir and running it in production, serving live requests. This book will help you fll this gap by going into detail on several aspects of how Elixir works and showing concrete examples of how to apply the concepts learned to a fully fledged application. In this book, you will learn how to build a rock-solid application, beginning by using Mix to create a new project. Then you will learn how the use of Erlang's OTP, along with the Elixir abstractions that run on top of it (such as GenServer and GenStage), that allow you to build applications that are easy to parallelize and distribute. You will also master supervisors (and supervision trees), and comprehend how they are the basis for building fault-tolerant applications. Then you will use Phoenix to create a web interface for your application. Upon fnishing implementation, you will learn how to take your application to the cloud, using Kubernetes to automatically deploy, scale, and manage it. Last, but not least, you will keep your peace of mind by learning how to thoroughly test and then monitor your application. What you will learn Use Elixir tools, including IEx and Mix Find out how an Elixir project is structured and how to create umbrella applications Discover the power of supervision trees, the basis for fault-tolerance Create a Domain-Specifc Language (DSL) that abstracts complexity Create a blazing-fast web interface for your application with Phoenix Set up an automatic deployment process for the cloud Monitor your application and be warned if anything unexpected happens Who this book is for Mastering Elixir is for you if you have experience in Elixir programming and want to take it to the next level. This Elixir book shows you how to build, deploy, and maintain robust applications, allowing you to go from tinkering with Elixir on side projects to using it in a live environment. However, no prior knowledge of Elixir is required to enjoy the complex topics covered in the book.