Catel - Part 4 of n: Unit testing with Catel

// --------------------------------------------------------------------------------------------------------------------
// <copyright file="FlowDocumentExtensions.cs" company="Catel development team">
//   Copyright (c) 2008 - 2011 Catel development team. All rights reserved.
// </copyright>
// <summary>
//   Extension methods for <see cref="FlowDocument" />.
// </summary>
// --------------------------------------------------------------------------------------------------------------------

using System;
using System.IO;
using System.Windows.Documents;
using System.Windows.Markup;
using Microsoft.Win32;

namespace Catel.Windows.Documents
{
    /// <summary>
    /// Extension methods for <see cref="FlowDocument"/>.
    /// </summary>
    public static class FlowDocumentExtensions
    {
        /// <summary>
        /// Clones a <see cref="FlowDocument"/> object.
        /// </summary>
        /// <param name="flowDocument">FlowDocument to copy.</param>
        /// <returns>A copy of the FlowDocument.</returns>
        public static FlowDocument CloneFlowDocument(this FlowDocument flowDocument)
        {
            FlowDocument finalFlowDocument = null;

            if (flowDocument == null)
            {
                return finalFlowDocument;
            }

            using (Stream stream = new MemoryStream())
            {
                XamlWriter.Save(flowDocument, stream);

                stream.Position = 0;

                finalFlowDocument = (FlowDocument)XamlReader.Load(stream);
            }

            return finalFlowDocument;
        }

        /// <summary>
        /// Saves a <see cref="FlowDocument"/> to a file.
        /// </summary>
        /// <param name="flowDocument"><see cref="FlowDocument"/> to save.</param>
        public static void SaveFlowDocument(this FlowDocument flowDocument)
        {
            SaveFileDialog saveFile = new SaveFileDialog();
            FileStream xamlFile = null;
            saveFile.Filter = "FlowDocument Files (*.xaml)|*.xaml|All Files (*.*)|*.*";
            if (saveFile.ShowDialog() ?? false)
            {
                try
                {
                    xamlFile = saveFile.OpenFile() as FileStream;
                }
                catch (Exception e)
                {
                    String error = "There was an error opening the file:\n\n";
                    error += saveFile.FileName;
                    error += "\n\nException details:\n\n";
                    error += e.Message;
                    System.Windows.MessageBox.Show(error);
                    return;
                }

                if (xamlFile == null)
                {
                    return;
                }

                XamlWriter.Save(flowDocument, xamlFile);
                xamlFile.Close();
            }
        }
    }
}