/// <summary>
        /// Enables mocking of calls to this class.
        /// </summary>
        /// 
        /// <remarks>
        /// The calling class should pass in a class that derives from this
        /// class and overrides the calls to be mocked. 
        /// </remarks>
        /// 
        /// <param name="mock">The mocking class.</param>
        /// 
        /// <exception cref="InvalidOperationException">
        /// There is already a mock registered for this class.
        /// </exception>
        /// 
        public static void EnableMock(HealthVaultPlatformAlternateId mock)
        {
            Validator.ThrowInvalidIf(_saved != null, "ClassAlreadyMocked");

            _saved = _current;
            _current = mock;
        }
        /// <summary>
        /// Removes mocking of calls to this class.
        /// </summary>
        /// 
        /// <exception cref="InvalidOperationException">
        /// There is no mock registered for this class.
        /// </exception>
        /// 
        public static void DisableMock()
        {
            Validator.ThrowInvalidIfNull(_saved, "ClassIsntMocked");

            _current = _saved;
            _saved = null;
        }