How to compare empty objects for equivalency

[FLAMESpl]

Assertion .Should().BeEquivalentTo() throws when object to compare has no members and I can't find a way to overcome this. Does anyone know a solution? Here is my code with xunit it is fairly simple:

using FluentAssertions;

namespace TestProject;

public abstract class Strategy { }

public class NoOperationStrategy : Strategy { }

public class NumberStrategy : Strategy
{
    public int Number { get; }

    public NumberStrategy(int number)
    {
        Number = number;
    }
}

public class UnitTest
{
    [Fact]
    public void Test()
    {
        SomeMethod().Should().BeEquivalentTo(
            new Strategy[] { new NoOperationStrategy(), new NumberStrategy(1), new NumberStrategy(2) },
            cfg => cfg.IncludingAllRuntimeProperties());
    }

    private IEnumerable<Strategy> SomeMethod() => new Strategy[]
    {
        new NoOperationStrategy(),
        new NumberStrategy(1),
        new NumberStrategy(2)
    };
}

I would expect empty non-null object to be always equivalent to empty non-null object.

[jnyrup]

Here's a workaround for the described case.
To add IEquivalencySteps globally in a thread-safe manner, see https://fluentassertions.com/extensibility/#thread-safety

class NoOperationStrategyStep : IEquivalencyStep
{
    public EquivalencyResult Handle(Comparands comparands, IEquivalencyValidationContext context,
        IEquivalencyValidator nestedValidator)
    {
        if (comparands.Expectation is NoOperationStrategy && comparands.Subject is NoOperationStrategy)
        {
            return EquivalencyResult.AssertionCompleted;
        }

        return EquivalencyResult.ContinueWithNext;
    }
}

SomeMethod().Should().BeEquivalentTo(
    new Strategy[] { new NoOperationStrategy(), new NumberStrategy(1), new NumberStrategy(2) },
    opt => opt.IncludingAllRuntimeProperties().Using(new NoOperationStrategyStep()));

[FLAMESpl]

good to know about this feature