Catel - Part 4 of n: Unit testing with Catel

// --------------------------------------------------------------------------------------------------------------------
// <copyright file="PropertyHelper.cs" company="Catel development team">
//   Copyright (c) 2008 - 2011 Catel development team. All rights reserved.
// </copyright>
// <summary>
//   Property helper class.
// </summary>
// --------------------------------------------------------------------------------------------------------------------

using System;
using System.Reflection;
using Catel.Properties;
using log4net;

namespace Catel.Reflection
{
    /// <summary>
    /// Property helper class.
    /// </summary>
    public static class PropertyHelper
    {
        #region Variables
        /// <summary>
        /// The <see cref="ILog">log</see> object.
        /// </summary>
        private static readonly ILog Log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
        #endregion

        /// <summary>
        /// Gets the property value of a specific object.
        /// </summary>
        /// <param name="obj">The object.</param>
        /// <param name="property">The property.</param>
        /// <returns>
        /// The property value or <c>null</c> if no property can be found.
        /// </returns>
        /// <exception cref="ArgumentNullException">when <paramref name="obj"/> is <c>null</c>.</exception>
        /// <exception cref="PropertyNotFoundException">when <paramref name="obj"/> is not found or not publicly available.</exception>
        /// <exception cref="CannotGetPropertyValueException">when the property value cannot be read.</exception>
        public static object GetPropertyValue(object obj, string property)
		{
			if (obj == null)
			{
				throw new ArgumentNullException("obj");
			}

			Type type = obj.GetType();
			PropertyInfo propertyInfo = type.GetProperty(property);
			if (propertyInfo == null)
			{
                Log.Error(TraceMessages.PropertyNotFoundOnObjectProbablyInvalidMapping, property, type);
			    throw new PropertyNotFoundException(property);
			}

			// Return property value if available
			if (!propertyInfo.CanRead)
			{
                Log.Error(TraceMessages.CannotReadProperty, type, property);
                throw new CannotGetPropertyValueException(property);
			}

            try
            {
                return propertyInfo.GetValue(obj, null);
            }
            catch (MethodAccessException)
            {
                Log.Error(TraceMessages.CannotReadProperty, type, property);
                throw new CannotGetPropertyValueException(property);
            }
		}

        /// <summary>
        /// Gets the property value of a specific object.
        /// </summary>
        /// <typeparam name="TValue">The type of the value.</typeparam>
        /// <param name="obj">The object.</param>
        /// <param name="property">The property.</param>
        /// <returns>
        /// The property value or <c>null</c> if no property can be found.
        /// </returns>
        /// <exception cref="ArgumentNullException">when <paramref name="obj"/> is <c>null</c>.</exception>
        /// <exception cref="PropertyNotFoundException">when <paramref name="obj"/> is not found or not publicly available.</exception>
        /// <exception cref="CannotGetPropertyValueException">when the property value cannot be read.</exception>
        public static TValue GetPropertyValue<TValue>(object obj, string property)
        {
            return (TValue)GetPropertyValue(obj, property);
        }

        /// <summary>
        /// Sets the property value of a specific object.
        /// </summary>
        /// <param name="obj">The object.</param>
        /// <param name="property">The property.</param>
        /// <param name="value">The value.</param>
        /// <exception cref="ArgumentNullException">when <paramref name="obj"/> is <c>null</c>.</exception>
        /// <exception cref="PropertyNotFoundException">when <paramref name="obj"/> is not found or not publicly available.</exception>
        /// <exception cref="CannotSetPropertyValueException">when the property value cannot be written.</exception>
        public static void SetPropertyValue(object obj, string property, object value)
        {
            if (obj == null)
            {
                throw new ArgumentNullException("obj");
            }

            Type type = obj.GetType();
            PropertyInfo propertyInfo = type.GetProperty(property);
            if (propertyInfo == null)
            {
                Log.Error(TraceMessages.PropertyNotFoundOnObjectProbablyInvalidMapping, property, type);
                throw new PropertyNotFoundException(property);
            }

            if (!propertyInfo.CanWrite)
            {
                Log.Error(TraceMessages.CannotWriteProperty, type, property);
                throw new CannotSetPropertyValueException(property);
            }

            try
            {
                propertyInfo.SetValue(obj, value, null);   
            }
            catch (MethodAccessException)
            {
                Log.Error(TraceMessages.CannotWriteProperty, type, property);
                throw new CannotSetPropertyValueException(property);
            }
        }
    }
}