> If you can write a unit test that makes your code throw UnreachableException, you almost certainly should be throwing a different exception. ArgumentNullExce

> If you can write a unit test that makes your code throw UnreachableException, you almost certainly should be throwing a different exception. ArgumentNullException, InvalidOperationException... There's plenty that have been around since the beginning. What's more important, that I didn't see in the first two examples, are useful error messages.