Disk-file dependency helper for restarting ASP.NET Environment on disk-file change

DiskFileDependencyHelper.cs

public static class DiskFileDependencyHelper
{
    public static void AddRestartWatch(string filePath)
    {
        var fileInfo = new FileInfo(filePath);
        if (fileInfo.Directory == null)
        {
            throw new FileNotFoundException("File or folder not found.", filePath);
        }

        var configWatcher = new FileSystemWatcher(fileInfo.Directory.FullName, fileInfo.Name);
        configWatcher.Changed += ConfigWatcherChanged;
        configWatcher.EnableRaisingEvents = true;
    }

    private static void ConfigWatcherChanged(object sender, FileSystemEventArgs e)
    {
        HttpRuntime.UnloadAppDomain();
    }
}