assert-fail.cs

using System;
using System.Diagnostics;
using System.IO;

namespace Baconator
{
    class Program
    {
        static void Main(string[] args)
        {
            BaconConfigurator.Instance.DoSomethingWithBacon();
        }
    }

    public class BaconConfigurator
    {
        public static BaconConfigurator Instance { get; } = new BaconConfigurator();
        private static readonly string _path = Path.Combine(CONFIG.GetConfig("Root"), "bacon.xml");
        private BaconConfigurator()
        {
            Debug.Assert(_path != null);
        }

        public void DoSomethingWithBacon()
        {
           var exists = File.Exists(_path);
            Debug.WriteLine(exists);
        }
    }

    public class CONFIG
    {
        public static string GetConfig(string path)
        {
            switch (path)
            {
                case "Root":
                    return @"C:\\bacon\\";
                default:
                    throw new ArgumentException("Invalid path.", nameof(path));
            }
        }
    }
}

assert-pass.cs

using System;
using System.Diagnostics;
using System.IO;

namespace Baconator
{
    class Program
    {
        static void Main(string[] args)
        {
            BaconConfigurator.Instance.DoSomethingWithBacon();
        }
    }

    public class BaconConfigurator
    {
        private static readonly string _path = Path.Combine(CONFIG.GetConfig("Root"), "bacon.xml");
        public static BaconConfigurator Instance { get; } = new BaconConfigurator();
        private BaconConfigurator()
        {
            Debug.Assert(_path != null);
        }

        public void DoSomethingWithBacon()
        {
           var exists = File.Exists(_path);
            Debug.WriteLine(exists);
        }
    }

    public class CONFIG
    {
        public static string GetConfig(string path)
        {
            switch (path)
            {
                case "Root":
                    return @"C:\\bacon\\";
                default:
                    throw new ArgumentException("Invalid path.", nameof(path));
            }
        }
    }
}