CodeFault

A library to check that compilation fails on code fragments:

using (var code = new Compiler("C#"))
{
    code.Reference<int>()	// reference System.dll assembly
        .Compile(@"
using System;

class Foo<T> where T : Delegate
{
}")
        .FailsWith(code.Error("CS0702", line:4)); // Constraint cannot be special class 'Delegate'
}

If the compilation does not have that error at the given line, it will throw an exception. This allows unit testing abstractions that are supposed to prevent certain errors at compile-time.