Testing with F#

The most important stage in the application development life cycle is testing, and modern-day testing methodologies like TDD give the developer the flexibility to plan their tests simultaneously while coding. This testing process includes unit testing, integration testing, system testing, and acceptance testing. Before any application is deployed, these four steps are necessary so that applications perform the exact tasks they are designed for. With test-driven development, we get an API that not only validates the correctness of our code, but also provides better understanding. You can write useful code in F# without touching core code, and writing tests is a great way to start. Not only does F# have a more compact syntax, it also has many nice features, such as the "double backtick" syntax that makes test names much more readable.

Starting with an introduction to the concepts behind test automation, you will learn how to write good quality code and test your F# Applications. You will learn how to set up your testing environment for unit testing and how to execute your test suite within and outside different Visual Studio frameworks such as NUnit and xUnit, as well as how to use FsUnit to build tests. You will also dive into testing in isolation, creating test doubles with the mocking framework Foq, and testing by mocking the database context using type providers.

Over the course of this book, you will learn how integration testing is performed in a functional application and gain insight into the best practices for developing a sustainable test suite. You will also learn how you can use F# to test stored procedures in a database, work with migrations in order to test database integrations in isolation, generate test data with FsCheck, and test web services interactively with F#. You will learn how to apply these techniques with the Agile methodology and turn your tests into specifications to maximize their efficiency.

Towards the end of this book, you will discover the problems that might arise while testing, and learn how to make your tests stable. By the end of this book, you will be able to test your F# applications and yield high-quality code.