Using FluentAssertions to find null in object graph

Question

I am trying to use the extensibility APIs (IEquivalencyStep) in FluentAssertions to detect if an object recursively contains any property with null value. The object type is unknown at compile time.

I have come up with this:

public static class ObjectAssertionsExtensions
{
    public static void BeWithoutNullValues(this ObjectAssertions objectAssertions)
    {
        objectAssertions.BeEquivalentTo(objectAssertions.Subject, options => options.Using(new NotNullEquivalencyStep()));
    }

    private class NotNullEquivalencyStep : IEquivalencyStep
    {
        public EquivalencyResult Handle(Comparands comparands, IEquivalencyValidationContext context, IEquivalencyValidator nestedValidator)
        {
            comparands.Subject.Should().NotBeNull(context.Reason.FormattedMessage, context.Reason.Arguments);
            return EquivalencyResult.ContinueWithNext;
        }
    }
}

that can be called like this:

instance.Should().BeWithoutNullValues();

But it doesn't really work as expected - I think one of the default equivalency steps make the test pass when it should fail because I am using the subject as expectation (they are equal by reference).

However, I have found that if I modify the global equivalency assertion options, It works:

public static void BeWithoutNullValues(this ObjectAssertions objectAssertions)
{
    AssertionOptions.AssertEquivalencyUsing(options => options.Using(new NotNullEquivalencyStep()));
    objectAssertions.BeEquivalentTo(objectAssertions.Subject);
}

Modifying the global options is not an acceptable solution, so I have two questions:

• Is it possible to disable the default equivalency steps without modifying the global options?
• If not, is it possible to reset the global options afterwards (i.e. de-registering NotNullEquivalencyStep)?