/// <summary>
        /// Sets the instance used for reading and writing settings to <paramref name="settingsInternal"/>, and returns
        /// the previous instance.
        /// THIS IS FOR TESTING PURPOSES ONLY.
        /// </summary>
        public static SettingsInternal ExchangeInstance(SettingsInternal settingsInternal)
        {
            var previousSettingsInternal = _instance;

            _instance = settingsInternal;
            return(previousSettingsInternal);
        }
 static Settings()
 {
     _instance = new SettingsInternal(FileSystem.Singleton, DateTimeProvider.Singleton);
 }