How to exclude members from BeEquivalentTo that are null

Hi,

I have code like this:

var user = table.CreateInstance<User>();
userDTO.Should().BeEquivalentTo(user, options => options.ExcludingMissingMembers());

user:

example userDTO:

{ "email": "testuser01@kl;kl;.com", "password": "nn91PKBrv99yQc/uNqTM2", "id": 2, "name": "Ervin Howell", "username": "Antonette", "address": { "street": "Victor Plains", "suite": "Suite 879", "city": "Wisokyburgh", "zipcode": "90566-7771", "geo": { "lat": "-43.9509", "lng": "-34.4618" } }, "phone": "010-692-6593 x09125", "website": "anastasia.net", "company": { "name": "Deckow-Crist", "catchPhrase": "Proactive didactic contingency", "bs": "synergize scalable supply-chains" } },

I want assert only fields that are not null in user but get exception:

'Expected member Email to be <null>, but found "[e-mail]". Expected member Password to be <null>, but found "O5jG6//tFKinn91PKBrv99yQc/uNqTM2". Expected member Company to be <null>, but found

Null values still are checked. How to not check null values?

[jnyrup]

Here’s an example on how to recursively ignore members from the expectation, when their runtime value is null.

class User
{
    public string Name { get; set; }

    public string Address { get; set; }
}

class UserDTO
{
    public string Name { get; set; }

    public string Address { get; set; }
}

class IgnoreNullMembersInExpectation : IEquivalencyStep
{
    public bool CanHandle(IEquivalencyValidationContext context, IEquivalencyAssertionOptions config) => context.Expectation is null;

    public bool Handle(IEquivalencyValidationContext context, IEquivalencyValidator parent, IEquivalencyAssertionOptions config) => true;
}

[TestClass]
public class IgnoreNullMembers
{
    [TestMethod]
    public void User_and_UserDTO_only_differs_by_null_property()
    {
        // Arrange
        var userDTO = new UserDTO
        {
            Name = "foo",
            Address = "bar"
        };

        var user = new User
        {
            Name = "foo",
            Address = null
        };

        // Assert
        userDTO.Should().BeEquivalentTo(user, opt => opt
            .Using(new IgnoreNullMembersInExpectation()));
    }

    [TestMethod]
    public void User_and_UserDTO_differs_by_non_null_property()
    {
        // Arrange
        var userDTO = new UserDTO
        {
            Name = "foo",
            Address = "bar"
        };

        var user = new User
        {
            Name = "baz",
            Address = null
        };

        // Assert
        userDTO.Should().NotBeEquivalentTo(user, opt => opt
            .Using(new IgnoreNullMembersInExpectation()));
    }
}

[dennisdoomen]

To be honest, I think it’s a scary way to compare two types. Just imagine what happens if Username suddenly become null. But if your intention is to compare only certain properties, you can pass in an anonymous type instead of user that only defines the properties that you care about.