Unit Testing a Silverlight View Model Style Modal Popup

// Copyright (c) 2010
// by OpenLight Group
// http://openlightgroup.net/
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated 
// documentation files (the "Software"), to deal in the Software without restriction, including without limitation 
// the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and 
// to permit persons to whom the Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all copies or substantial portions 
// of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED 
// TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 
//
// CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
// DEALINGS IN THE SOFTWARE.

using System;
using System.ComponentModel;
using System.Windows.Input;
using System.Windows.Controls;

namespace MVVMPopUp
{
    public class PopUpViewModel : INotifyPropertyChanged
    {
        private ChildWindow PopUP;

        public PopUpViewModel()
        {
            // Set the command property
            SetPopUpCommand = new DelegateCommand(SetPopUp, CanSetPopUp);
            OKButtonCommand = new DelegateCommand(OKButton, CanOKButton);
            CancelButtonCommand = new DelegateCommand(CancelButton, CanCancelButton);
        }

        // Commands

        #region SetPopUpCommand
        public ICommand SetPopUpCommand { get; set; }
        public void SetPopUp(object param)
        {
            PopUP = (ChildWindow)param;
        }

        private bool CanSetPopUp(object param)
        {
            return true;
        }
        #endregion

        #region OKButtonCommand
        public ICommand OKButtonCommand { get; set; }
        public void OKButton(object param)
        {
            PopUP.DialogResult = true;
        }

        private bool CanOKButton(object param)
        {
            return true;
        }
        #endregion

        #region CancelButtonCommand
        public ICommand CancelButtonCommand { get; set; }
        public void CancelButton(object param)
        {
            PopUP.DialogResult = false;
        }

        private bool CanCancelButton(object param)
        {
            return true;
        }
        #endregion

        // Properties

        #region SelectedPopUpValueProperty
        private string _SelectedPopUpValueProperty;
        public string SelectedPopUpValueProperty
        {
            get
            {
                return this._SelectedPopUpValueProperty;
            }
            set
            {
                this._SelectedPopUpValueProperty = value;
                this.NotifyPropertyChanged("SelectedPopUpValueProperty");
            }
        }
        #endregion

        #region DefaultValueProperty
        private string _DefaultValueProperty;
        public string DefaultValueProperty
        {
            get
            {
                return this._DefaultValueProperty;
            }
            set
            {
                this._DefaultValueProperty = value;
                this.NotifyPropertyChanged("DefaultValueProperty");
                SelectedPopUpValueProperty = this._DefaultValueProperty;
            }
        }
        #endregion

        // Utility
		   
        #region INotifyPropertyChanged
        public event PropertyChangedEventHandler PropertyChanged;

        private void NotifyPropertyChanged(String info)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(info));
            }
        }
        #endregion        
    }
}