Ploeh AutoFixture was unable to create an instance from System.Runtime.Serialization.ExtensionDataObject

Question

We have an MVC project with references to WCF services. Those references added (ExtensionDataObject)ExtensionData property to every DTO and Response object and

Answer 1

The easiest way to do it is:

fixture.Register<ExtensionDataObject>(() => null);

That registers to AutoFixture a specific way to initialize all the ExtensionDataObject, with the Func given. In this case the Func always returns null so you are good to go.

Answer 2

To make it bit DRYer and CTRL+C friendly, here is Spiros Dellaportases (thanks!) answer wrapped in fixture Customization:

public class OmitExtensionDataObjectPropertyCustomization : ICustomization
{
    public void Customize(IFixture fixture)
    {
        fixture.Register<ExtensionDataObject>(() => null);
    }
}

Answer 3

I hope someone will find it useful, I've managed to get it to work with the PropertyTypeOmitter class as per the this thread:

public void Test()
{
    var fixture = new Fixture();
    fixture.Customizations.Add(
        new PropertyTypeOmitter(
            typeof(ExtensionDataObject)));

    var person = fixture.CreateAnonymous<Person>();
}

internal class PropertyTypeOmitter : ISpecimenBuilder
{
    private readonly Type type;

    internal PropertyTypeOmitter(Type type)
    {
        if (type == null)
            throw new ArgumentNullException("type");

        this.type = type;
    }

    internal Type Type
    {
        get { return this.type; }
    }

    public object Create(object request, ISpecimenContext context)
    {
        var propInfo = request as PropertyInfo;
        if (propInfo != null && propInfo.PropertyType == type)
            return new OmitSpecimen();

        return new NoSpecimen();
    }
}