ViewModelPropertiesImplementNotifyPropertyChangedAndAreInUIProject.cs

    public class ViewModelPropertiesImplementNotifyPropertyChangedAndAreInUIProject : IConvention<Types>
    {
        public void Execute(Types data, IConventionResultContext result)
        {
            var notifyPropertyChanged = typeof(INotifyPropertyChanged);
            var viewModelType = typeof(ViewModelBase);
            var viewModels = data.TypesToVerify.Where(viewModelType.IsAssignableFrom);
            var allPropertyTypes = GetPropertyTypes(viewModels, new List<Type>()).ToArray();
            var failingData = allPropertyTypes.Where(t => !notifyPropertyChanged.IsAssignableFrom(t));

            result.Is("Types which are publically exposed from ViewModel must inherit from INotifyPropertyChanged and live in the Toolbar.UI project",
                failingData);
        }

        public string ConventionReason
        {
            get { return "This ensures that all properties off a viewmodel can be bound to and raise property changed notifications properly"; }
        }

        private IEnumerable<Type> GetPropertyTypes(IEnumerable<Type> typesToVerify, List<Type> knownTypes)
        {
            foreach (var type in typesToVerify)
            {
                var propertyTypes = type.GetProperties()
                    .Select(p =>
                    {
                        if (p.PropertyType.IsArray)
                            return p.PropertyType.GetElementType();
                        return p.PropertyType;
                    })
                    .Where(p =>  p.IsConcreteClass())
                    .Except(knownTypes)
                    .ToArray();
                foreach (var propertyType in propertyTypes)
                {
                    var ienumerable = propertyType.GetInterfaces().FirstOrDefault(t=>t.IsGenericType && t.GetGenericTypeDefinition() == typeof(IEnumerable<>));
                    if (ienumerable != null)
                    {
                        var ienumerableType = ienumerable.GetGenericArguments()[0];
                        if (ienumerableType.Namespace == null || !ienumerableType.Namespace.StartsWith("System"))
                        {
                            yield return ienumerableType;
                        }
                    }
                    else if (propertyType.Namespace == null || !propertyType.Namespace.StartsWith("System"))
                    {
                        yield return propertyType;
                    }
                    knownTypes.Add(propertyType);
                }
                foreach (var propertyType in GetPropertyTypes(propertyTypes, knownTypes))
                {
                    knownTypes.Add(propertyType);
                    yield return propertyType;
                }
            }
        }
    }