Catel - Part 4 of n: Unit testing with Catel

// --------------------------------------------------------------------------------------------------------------------
// <copyright file="IsSelectedConverter.cs" company="Catel development team">
//   Copyright (c) 2008 - 2011 Catel development team. All rights reserved.
// </copyright>
// <summary>
//   Converts a selected value to either true of false
// </summary>
// --------------------------------------------------------------------------------------------------------------------

using System;
using System.Globalization;
using System.Windows.Data;

namespace Catel.Windows.Data.Converters
{
	/// <summary>
	/// Converts a selected value to either true of false.
	/// </summary>
	/// <remarks>
	/// This converter is very usefull when a mutual exclusive selection must be made
	/// Original code found at http://geekswithblogs.net/claraoscura/archive/2008/10/17/125901.aspx
	/// </remarks>
#if !SILVERLIGHT
    [ValueConversion(typeof(bool?), typeof(bool))]
#endif
    public class IsSelectedConverter : IValueConverter
    {
		/// <summary>
		/// Converts a value.
		/// </summary>
		/// <param name="value">The value produced by the binding source.</param>
		/// <param name="targetType">The type of the binding target property.</param>
		/// <param name="parameter">The converter parameter to use.</param>
		/// <param name="culture">The culture to use in the converter.</param>
		/// <returns>
		/// A converted value. If the method returns null, the valid null value is used.
		/// </returns>
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            // Get parameter
		    bool param = true;
            if (parameter is string)
            {
                bool.TryParse((string) parameter, out param);
            }

            // Return value
            return (value == null) ? false : !((bool)value ^ param);
        }

		/// <summary>
		/// Converts a value.
		/// </summary>
		/// <param name="value">The value that is produced by the binding target.</param>
		/// <param name="targetType">The type to convert to.</param>
		/// <param name="parameter">The converter parameter to use.</param>
		/// <param name="culture">The culture to use in the converter.</param>
		/// <returns>
		/// A converted value. If the method returns null, the valid null value is used.
		/// </returns>
        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            // Get parameter
            bool param = true;
            if (parameter is string)
            {
                bool.TryParse((string)parameter, out param);
            }

            // Return value
            return !((bool)value ^ param);
        }
    }
}