Property-Based Testing with Proper, Erlang, and Elixir

Find Bugs Before Your Users Do

出版社 Pragmatic Bookshelf
発売日 2019/02/05
ページ数 376
ISBN-13 9781680506211
お届け日 通常 02月15日~02月22日

通常価格 ¥5,060

税込 配送料は購入手続き時に計算されます。


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 Elixir
  • For Erlang tests: Erlang/OTP >= 20.0, with Rebar >= 3.4.0
  • For Elixir tests: Erlang/OTP >= 20.0, Elixir >= 1.5.0



ほとんどのテストは、開発者が期待した通りにコードが振る舞うことを示すだけなので、特別な条件やエッジケースが現れたときに著者と同じ盲点を抱えています。PropEr で書かれたプロパティテストを使って、異なるものを見る方法を学びましょう。




  • Erlangの基本的な知識(オプションでElixirも可
  • Erlangテストの場合。Erlang/OTP >= 20.0, Rebar >= 3.4.0でのテスト
  • Elixirテストの場合。Erlang/OTP >= 20.0, Elixir >= 1.5.0