Adding ExpectedObjects to NSubstitute

gistfile1.txt

This adds a new Arg.ShouldMatch<T> method that uses expected objects to verify the received argument matches the expected object. For example the code below gives an error message of "ReceivedCallsException: Expected to receive exactly 1 call matching:
	Blah(For Thing.Stuff, expected "Whatever2" but found "Whatever".
For Thing.OtherStuff, expected "abcd2" but found "abcd".
)
Actually received no matching calls.
Received 1 non-matching call (non-matching arguments indicated with '*' characters):
	Blah(*Thing*)"

void Main()
{
	var blah = Substitute.For<IBlah>();
	
	blah.Blah(new Thing { Stuff = "Whatever", OtherStuff = "abcd" });
	
	blah.Received(1).Blah(Arg.ShouldMatch<Thing>(new { Stuff = "Whatever2", OtherStuff = "abcd2" }));
}

public interface IBlah
{
	void Blah(Thing thing);
}

public class Thing
{
	public string Stuff { get;set; }
	public string OtherStuff { get;set; }
}

What we have been doing is something like:

Model persistModel = null;

_repository.WhenForAnyArgs(r => r.Store(null))
.Do(info => persistModel = info.Arg<IList>().FirstOrDefault());

// Act

new
{
Id = _theId,
Thing = "something"
}.ToExpectedObject().ShouldMatch(persistModel);

This will tell us each individual property that doesn't match along with the expected value or indicate that the object is null (without a NullReferenceException). So 1 test can show all the issues in the data item at once. It's just really ugly to do it this way. It's also messy if I want to validate multiple items.

From your description I thing that your solution would work in the simpler cases. I'm not sure how effective it would be if the parameter is a collection where I want to validate properties on multiple entries. It might be better for some checks such as verifying that a collection item is of a specific type which Expected Objects doesn't seem to support.

Really the key point here is that the error message from what we're doing isn't just a "it failed", it lists everything that has failed which makes fixing things a lot easier. My real driver is to be able to do that without the When/Do overhead.