Catel - Part 4 of n: Unit testing with Catel

// --------------------------------------------------------------------------------------------------------------------
// <copyright file="ContainsItemsConverter.cs" company="Catel development team">
//   Copyright (c) 2008 - 2011 Catel development team. All rights reserved.
// </copyright>
// <summary>
//   Converter that converts whether a collection contains items or not.
// </summary>
// --------------------------------------------------------------------------------------------------------------------

using System;
using System.Collections;
using System.Windows.Data;

namespace Catel.Windows.Data.Converters
{
	/// <summary>
	/// Converter that converts whether a collection contains items or not.
	/// </summary>
#if !SILVERLIGHT
	[ValueConversion(typeof(IEnumerable), typeof(bool))]
#endif
	public class ContainsItemsConverter : IValueConverter
	{
		/// <summary>
		/// Convert the count of a collection to true or false, depending on whether the collection contains items.
		/// </summary>
		/// <param name="value">Values to check for. Both collections and arrays are supported.</param>
		/// <param name="targetType">Not used.</param>
		/// <param name="parameter">Not used.</param>
		/// <param name="culture">Not used.</param>
		/// <returns>True when at least 1 item is inside the collection or array, otherwise false.</returns>
		public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
		{
			// Check if we have a valid value
			if (value == null)
			{
			    return false;
			}

			// Check if the value is a collection
			ICollection collection = value as ICollection;
			if (collection != null)
			{
			    return (collection.Count > 0);
			}

			// Check if the value is an IEnumerable
			IEnumerable enumerable = value as IEnumerable;
			if (enumerable != null)
			{
				foreach (object obj in enumerable)
				{
					// We have at least 1 item
					return true;
				}
			}

			// Not supported, thus false
			return false;
		}

		/// <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>
		/// <remarks>
		/// This method is not supported.
		/// </remarks>
		public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
		{
            return ConverterHelper.DoNothingBindingValue;
		}
	}
}