public void when_attempting_to_version_a_property_bag()
{
var originalAddress = "12345 Fake Street";
var subscriber = new SimpleMementoingClass()
{
Domainees = new List<DomainPropertyBag>()
{
new DomainPropertyBag(),
new DomainPropertyBag()
},
ChiefDomainee = new DomainPropertyBag(),
Address = originalAddress,
FirstName = "If only Customer Objects",
LastName = "were ever this simple"
};
var mementor = new Mementor();
var newAddress = "Changed Address!";
mementor.PropertyChange(subscriber, () => subscriber.Address);
//ohhh typing is a little weak here.
subscriber.Address = newAddress; //ahh, note the order matters of course.
subscriber.Address.Should().Be(newAddress);
mementor.Undo();
//and I cant undo specific changes, just the last one.
subscriber.Address.Should().Be(originalAddress);
//still, very cool.
//In terms of a deployed program, this is tough to implement.
//I like the pub-sub design of it, code is superbly clean.
}
/// <summary>
/// Marks an element index change event.
/// </summary>
/// <typeparam name="T">The generic type parameter of the collection.</typeparam>
/// <param name="mementor">The mementor object.</param>
/// <param name="collection">The collection object.</param>
/// <param name="element">The element whose index is being changed</param>
/// <param name="elementIndex">The index of the element being removed. If not supplied, will retrieve via <see cref="IList{T}.IndexOf"/>.</param>
public static void ElementIndexChange <T>(this Mementor mementor,
IList <T> collection, T element, int?elementIndex = null)
{
if (mementor.IsTrackingEnabled)
{
mementor.MarkEvent(new ElementIndexChangeEvent <T>(collection, element, elementIndex));
}
}
/// <summary>
/// Marks an element addition event.
/// </summary>
/// <typeparam name="T">The generic type parameter of the collection.</typeparam>
/// <param name="mementor">The mementor object.</param>
/// <param name="collection">The collection object.</param>
/// <param name="element">The element being added.</param>
public static void ElementAdd <T>(this Mementor mementor,
IList <T> collection, T element)
{
if (mementor.IsTrackingEnabled)
{
mementor.MarkEvent(new ElementAdditionEvent <T>(collection, element));
}
}
/// <summary>
/// Marks a property change event.
/// </summary>
/// <param name="mementor">The mementor object.</param>
/// <param name="target">The target object.</param>
/// <param name="propertyName">The name of the property.</param>
/// <param name="previousValue">The value to be restored to when undo.
/// If not supplied, will be retrieved directly from the <paramref name="target"/>.</param>
public static void PropertyChange(this Mementor mementor,
object target, string propertyName, object previousValue = null)
{
if (mementor.IsTrackingEnabled)
{
mementor.MarkEvent(new PropertyChangeEvent(target, propertyName, previousValue));
}
}
/// <summary>
/// Marks a property change event.
/// </summary>
/// <typeparam name="TProp">The type of the property.</typeparam>
/// <param name="mementor">The mementor object.</param>
/// <param name="target">The target object.</param>
/// <param name="propertySelector">The property selector expression.</param>
/// <param name="previousValue">The value to be restored to when undo.
/// If not supplied, will be retrieved directly from the <paramref name="target"/>.</param>
public static void PropertyChange <TProp>(this Mementor mementor,
object target, Expression <Func <TProp> > propertySelector, object previousValue = null)
{
if (mementor.IsTrackingEnabled)
{
PropertyChange(mementor, target, propertySelector.Name(), previousValue);
}
}
public void when_forcing_bad_things_via_expression()
{
var subscriber = new SimpleMementoingClass();
var mementor = new Mementor();
subscriber.Address = "Changed!";
Assert.Throws<InvalidCastException>(() => mementor.PropertyChange(subscriber, () => mementor.ToString()));
//aww duder and the exceptions arn't handled nicely here either, Linq at the wrong thing and get a generic Expression.OhgodohgodohgodException
//why not public void PropertyChange<TSubject, TTargetSite>(this TSubject subject, Func<TSubject, TTargetSite> transform...)
//would be mementor.PropertyChange(subscriber, sub => sub.SomeProp), would provide some additional typiing on the expression.
}
public void when_attempting_to_restore_an_externally_tracked_list()
{
var mementor = new Mementor(isEnabled: true);
var collection = new List<string>();
var item = "hey!";
mementor.ElementAdd(collection, item);//this is an extension method? Oh I see, he didnt want to put custom-list logic on Mementor. Nice.
//it also doesnt actually add the element to the list:
collection.Add(item);
collection.Should().HaveCount(1);
mementor.Undo();
//hmm, so it expects the caller to do the Add but it will handle the remove?
collection.Should().BeEmpty();
}