Anonymous type BeEquivalentTo behaviour

[uokitomer]

Hey guys, I noticed a weird behavior today using BeEquivalentTo, would you let me know if this is expected or if there is a work around:

I am using version 5.10.3

I have a class with the following set of properties

`public class ContactCreatedEvent()
{
public Guid ContactId { get; }

    public Guid PracticeId { get; } = Guid.NewGuid();

}`

I am asserting that my event should be equivalent to my expected event this way

contactCreatedEvent.Should().BeEquivalentTo(expectedEvent);

Where expected event is

var expectedEvent = new { ContactId = testContact.ContactId, };

As you can see expectedEvent is an anonymous type. If PracticeId is missing the assertion still pass.

I would expect that if there is a missing member in any of the two objects being compared the assertion should fail. I don't have too much experience using the library, I am not sure how the assertion works but I read the description of the method saying if any of the two objects have mismatch amount of properties the assertion should not pass, so I figured this might not be the desired behavior.

If I do the opposite (remove PracticeId from the ContactCreatedEvent and add it to the anonymous type) the assertion fails.

I am using anonymous type because this object actually has a lot of collection properties where I would like to exclude id fields given I don't care if they match but unfortunately I read here fluentassertions/fluentassertions#500 that there is no easy way to exclude all members of a collection from an assertion

Thank you!

[dennisdoomen]

Thank you for contacting us. The behavior you're seeing is by design. If your expectation has only a single property, then FA will only validate that your subject has the same property with the same (equivalent) value. This was a big change in 5.0.0.

But I do see the XML comments are a bit misleading. We'll update those.

[dennisdoomen]

Wait, why did you post this on the JSON version of FluentAssertions?

[uokitomer]

My bad! is definitely not a JSON comparison what I am doing, I think I was watching the project for something else and ended up posting my issue here.