Mocking out Environment.Exit

Question I came across recently on Twitter.

"How do I write a test when there's an Environment.Exit?! :("

Very good question... My answer was basically rewrite the code! A really quick way to do this is create a static action that will allow you to mock it out. What if I created a class called MyEnvironment with this Action:

    public class MyEnvironment
    {
        public static Action Exit = exitCode => Environment.Exit(exitCode);
    }

In code I can just replace the call with this:

    MyEnvironment.Exit(0);

And now, in my testing I can do something like this:

    MyEnvironment.Exit = exitCode => { };

Voila! No more interrupted tests :)