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Catel - Part 4 of n: Unit testing with Catel

, 28 Jan 2011
This article explains how to write unit tests for MVVM using Catel.
Catel-04_01-unittesting.zip
src
Catel.Articles.04 - Unit testing
Models
Properties
Settings.settings
Resources
Images
add.png
delete.png
edit.png
group.png
UI
Data
Converters
ViewModels
Windows
Catel.Articles.04 - Unit testing.Test
Models
Properties
UI
ViewModels
Catel.Articles.Base
Data
Attributes
Properties
Settings.settings
Resources
Images
CatenaLogic.png
Preview.png
Run.png
ShowCode.png
UI
Controls
Helpers
ViewModels
Windows
Catel.Core
Attributes
ClassDiagrams
DataObjectBase.cd
SavableDataObjectBase.cd
Collections
Helpers
ComponentModel
Data
Attributes
Exceptions
Interfaces
Diagnostics
Extensions
Helpers
Exceptions
Helpers
IO
Exceptions
IoC
LLBLGen
Log4net
Appender
Extensions
Helpers
MVVM
Commands
Interfaces
Exceptions
Services
EventArgs
Exceptions
Interfaces
ViewModels
Attributes
Interfaces
Properties
Reflection
Exceptions
Extensions
Helpers
Runtime
Serialization
Attributes
Helpers
Security
Cryptography
Helpers
Catel.Examples.Models
Properties
Catel.Examples.PersonApplication
Properties
Settings.settings
Resources
Images
add.png
delete.png
edit.png
group.png
UI
Data
Converters
ViewModels
Windows
Catel.Examples.Silverlight
Properties
Resources
Images
add.png
delete.png
edit.png
group.png
UI
Data
Converters
Pages
ViewModels
Windows
Catel.Examples.Silverlight.Web
Catel.Examples.Silverlight.Web.csproj.user
ClientBin
Properties
Catel.FxCop
Catel.Silverlight
Diagnostics
log4net
Core
MVVM
Commands
Services
ViewModels
Properties
Catel.Core
Catel.Windows
Reflection
Themes
Generic
Assets
Old
Windows
Controls
Data
Converters
Helpers
Helpers
Catel.Silverlight.Test
Properties
Catel.Silverlight.Test.Web
Catel.Silverlight.Test.Web.csproj.user
ClientBin
Properties
Catel.snk
Catel.Templates.WpfApplication
Properties
Settings.settings
UI
Controls
ViewModels
Windows
Catel.Templates.WpfItemTemplates
Properties
UI
Controls
ViewModels
Windows
Catel.Test
Collections
Convert
Data
Helpers
IO
MVVM
UI
ViewModels
Properties
Reflection
Runtime
Serialization
Security
Cryptography
Test References
Catel.Windows.accessor
Windows
Data
Converters
Catel.vsmdi
Catel.Windows
ClassDiagrams
ViewModelBase.cd
Collections
Extensions
Helpers
MVVM
Commands
Services
Test
UI
ViewModels
Properties
Settings.settings
Resources
Images
Add.png
ClearOutput.png
Edit.png
Error.png
Loading.gif
Preview.png
Remove.png
Save.png
TipOfTheDay.png
Warning.png
Themes
Aero
ExpressionDark
Assets
Generic
Assets
Controls
Jetpack
Assets
background.png
Old
SunnyOrange
Assets
Windows
Controls
Extensions
LinkLabel
StackGrid
Data
Converters
Helpers
Documents
Extensions
Extensions
Helpers
Input
Markup
Media
Effects
EmptyEffect
EmptyEffect.fx
EmptyEffect.ps
EmptyEffect.fx
GrayscaleEffect
GrayscaleEffect.fx
GrayscaleEffect.ps
Extensions
Imaging
Extensions
Windows
DataWindow
TipOfTheDay
Local.testsettings
Settings.StyleCop
TraceAndTestImpact.testsettings
// --------------------------------------------------------------------------------------------------------------------
// <copyright file="ManagedViewModel.cs" company="Catel development team">
//   Copyright (c) 2008 - 2011 Catel development team. All rights reserved.
// </copyright>
// <summary>
//   Represents a managed view model. A managed view model is watched for property changes. As soon as a change occurs in one of the
//   managed view models, all other interested view models are notified of the changes.
// </summary>
// --------------------------------------------------------------------------------------------------------------------

using System;
using System.Collections.Generic;
using System.ComponentModel;
using Catel.Properties;
using log4net;

namespace Catel.MVVM
{
	/// <summary>
	/// Represents a managed view model. A managed view model is watched for property changes. As soon as a change occurs in one of the
	/// managed view models, all other interested view models are notified of the changes.
	/// </summary>
	internal class ManagedViewModel
	{
		#region Variables
        /// <summary>
        /// The <see cref="ILog">log</see> object.
        /// </summary>
		private static readonly ILog Log = LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);

        /// <summary>
        /// List of alive view model instances.
        /// </summary>
        private readonly List<IViewModel> _viewModelInstances = new List<IViewModel>();

        /// <summary>
        /// List of alive view model instances that are interested in other view models.
        /// </summary>
        private readonly List<IViewModel> _interestedViewModels = new List<IViewModel>();
		#endregion

		#region Constructor & destructor
		/// <summary>
		/// Initializes a new instance of the <see cref="ManagedViewModel"/> class.
		/// </summary>
		/// <param name="viewModelType">Type of the view model.</param>
		public ManagedViewModel(Type viewModelType)
		{
			ViewModelType = viewModelType;
		}
		#endregion

		#region Properties
		/// <summary>
		/// Gets the type of the view model.
		/// </summary>
		/// <value>The type of the view model.</value>
		public Type ViewModelType { get; private set; }
		#endregion

		#region Methods
		/// <summary>
		/// Adds a view model instance to the list of instances.
		/// </summary>
		/// <param name="viewModel">The view model instance to add.</param>
		/// <exception cref="ArgumentNullException">When <paramref name="viewModel"/> is <c>null</c>.</exception>
		/// <exception cref="WrongViewModelTypeException">When <paramref name="viewModel"/> is not of the right type.</exception>
        public void AddViewModelInstance(IViewModel viewModel)
		{
			if (viewModel == null)
			{
			    throw new ArgumentNullException("viewModel");
			}

			if (viewModel.GetType() != ViewModelType)
			{
			    throw new WrongViewModelTypeException(viewModel.GetType(), ViewModelType);
			}

			lock (_viewModelInstances)
			{
				if (!_viewModelInstances.Contains(viewModel))
				{
					_viewModelInstances.Add(viewModel);

					viewModel.PropertyChanged += ViewModel_PropertyChanged;

					Log.Debug(TraceMessages.AddedViewModelInstance, _viewModelInstances.Count, ViewModelType);
				}
			}
		}

		/// <summary>
		/// Removes a view model instance from the list of instances.
		/// </summary>
		/// <param name="viewModel">The view model instance to remove.</param>
		/// <exception cref="ArgumentNullException">When <paramref name="viewModel"/> is <c>null</c>.</exception>
        public void RemoveViewModelInstance(IViewModel viewModel)
		{
			if (viewModel == null)
			{
			    throw new ArgumentNullException("viewModel");
			}

			lock (_viewModelInstances)
			{
				viewModel.PropertyChanged -= ViewModel_PropertyChanged;

				_viewModelInstances.Remove(viewModel);

				Log.Debug(TraceMessages.RemovedViewModelInstance, _viewModelInstances.Count, ViewModelType);
			}
		}

		/// <summary>
		/// Adds a view model to the list of interested view models for this view model type.
		/// </summary>
		/// <param name="viewModel">The view model instance that is interested in changes.</param>
		/// <exception cref="ArgumentNullException">When <paramref name="viewModel"/> is <c>null</c>.</exception>
        public void AddInterestedViewModel(IViewModel viewModel)
		{
			if (viewModel == null)
			{
			    throw new ArgumentNullException("viewModel");
			}

			lock (_interestedViewModels)
			{
				_interestedViewModels.Add(viewModel);

				viewModel.Closed += InterestedViewModel_Closed;

				Log.Debug(TraceMessages.AddedInterestedViewModel, viewModel.GetType(), ViewModelType, _interestedViewModels.Count);
			}
		}

		/// <summary>
		/// Removes a view model from the list of interested view models for this view model type.
		/// </summary>
		/// <param name="viewModel">The view model instance that is interested in changes.</param>
		/// <exception cref="ArgumentNullException">When <paramref name="viewModel"/> is <c>null</c>.</exception>
        public void RemoveInterestedViewModel(IViewModel viewModel)
		{
			if (viewModel == null)
			{
			    throw new ArgumentNullException("viewModel");
			}

			lock (_interestedViewModels)
			{
				viewModel.Closed -= InterestedViewModel_Closed;

				_interestedViewModels.Remove(viewModel);

				Log.Debug(TraceMessages.RemovedInterestedViewModel, viewModel.GetType(), ViewModelType, _interestedViewModels.Count);
			}
		}

		/// <summary>
		/// Handles the PropertyChanged event of the ViewModel instances.
		/// </summary>
		/// <param name="sender">The source of the event.</param>
		/// <param name="e">The <see cref="System.ComponentModel.PropertyChangedEventArgs"/> instance containing the event data.</param>
		private void ViewModel_PropertyChanged(object sender, PropertyChangedEventArgs e)
		{
			lock (_interestedViewModels)
			{
				foreach (ViewModelBaseWithoutServices viewModel in _interestedViewModels)
				{
					try
					{
						viewModel.ViewModelPropertyChanged((IViewModel)sender, e.PropertyName);
					}
					catch (Exception ex)
					{
						Log.Error(ex, TraceMessages.FailedToInformInterestedViewModelOfAViewModelChange);
					}	
				}
			}
		}

		/// <summary>
		/// Handles the Closed event of the InterestedViewModel instances.
		/// </summary>
		/// <param name="sender">The source of the event.</param>
		/// <param name="e">The <see cref="System.EventArgs"/> instance containing the event data.</param>
		private void InterestedViewModel_Closed(object sender, EventArgs e)
		{
            RemoveInterestedViewModel((IViewModel)sender);
		}
		#endregion
	}
}

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About the Author

Geert van Horrik
Software Developer CatenaLogic
Netherlands Netherlands
I am Geert van Horrik, and I have studied Computer Science in the Netherlands.
 
I love to write software using .NET (especially the combination of WPF and C#). I am also the lead developer of Catel, an open-source application development framework for WPF, Silverlight, WP7 and WinRT with the focus on MVVM.
 
I have my own company since January 1st 2007, called CatenaLogic. This company develops commercial and non-commercial software.
 
To download (or buy) applications I have written, visit my website: http://www.catenalogic.com
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