Unit testing

Unit testing is perhaps the easiest and most widely used technique to write automated tests. It consists of dividing our program into units, running each of these units in isolation, and then making sure that it produces the expected results. Ideally, tests should cover all units of our program so that no part of the code is left untested before deploying it to production. In functional programming, these units normally correspond to functions, and because there is no shared state, these functions can easily be tested in isolation from the rest of the program.

Unit tests with NUnit

There are several libraries that help us write unit tests for .NET. Here, we will use one of the most popular ones - NUnit. NUnit is compatible both with C# and F#, so if you have any previous development experience in C# , chances are that you already know how to use it. Writing tests with NUnit is very easy. Let's say you have a module (MyLib.fs) such as the following:

    module MyLib 
 
 ...