cannot find circular reference reported by autofixture

Question

I'm trying to validate my infrastructure. AutoFixture says I have a circular reference in my code and when I omit the behavior, it cannot cast the specimen to my object type.

Charting the solution dependencies yeilds no circular references. The ouput from autofixture appears to be giving me a path in which a domain object points to a domain object. I don't understand that... they are pretty plain.

I would just move on since I have a test that passes, but I'd really like to make sure I don't have an unwanted circular reference. I'm also concerned I won't be able to use AutoFixture later on for isolated components if it isn't building my simple domain object in this example.

Here is the test that succeeds:

[Fact]
[UseDataService(typeof(DatabaseVersionService))]
public void DataServiceGetsDatabaseVersionNonAutoFixture()
{
    var sut = new VersionClientProxy(new Uri(ConfigurationManager.AppSettings["DataServiceHostAddress"]));

    var expected = new DatabaseVersion()
    {
        MajorVersionId = 0,
        MinorVersionId = 0,
        BuildVersionId = 0,
        VersionId = 1
    };
     var actual = (from a in sut.DatabaseVersions
                  orderby a.VersionId descending
                  select a).FirstOrDefault();

    Assert.Equal(expected.MajorVersionId, actual.MajorVersionId);
    Assert.Equal(expected.MinorVersionId, actual.MinorVersionId);
    Assert.Equal(expected.BuildVersionId, actual.BuildVersionId);
    Assert.Equal(expected.VersionId, actual.VersionId);
}

Here is the test that fails:

[Fact]
[UseDataService(typeof(DatabaseVersionService))]
public void DataServiceGetsDatabaseVersion()
{
    var fixture = new Fixture();

    var sut = fixture.Build<VersionClientProxy>().FromFactory<VersionClientProxy>((x) =>
    {
        return new VersionClientProxy(new Uri(ConfigurationManager.AppSettings["DataServiceHostAddress"]));
    }).CreateAnonymous();

    var version = fixture.Build<DatabaseVersion>().FromFactory<DatabaseVersion>((x) =>
    {
        return new DatabaseVersion { MajorVersionId = 0, MinorVersionId = 0, BuildVersionId = 0, VersionId = 1 };
    }).CreateAnonymous();
    var expected = version.AsSource().OfLikeness<DatabaseVersion>();

    var actual = (from a in sut.DatabaseVersions
                  orderby a.VersionId descending
                  select a).FirstOrDefault();
    Assert.True(expected.Equals(actual));
}

Here is the client proxy (separate project references only data model project):

public class VersionClientProxy : DataServiceContext
{
    public VersionClientProxy(Uri serviceRoot)
        : base(serviceRoot, DataServiceProtocolVersion.V3)
    {
    }

    public IQueryable<DatabaseVersion> DatabaseVersions
    {
        get { return CreateQuery<DatabaseVersion>("DatabaseVersions"); }
    }
}

Here is the data service I spin up (service is in separate project references only data model project)

public class UseDataServiceAttribute : BeforeAfterTestAttribute
{
    private readonly DataServiceHost serviceHost;

    public UseDataServiceAttribute(Type serviceToHost)
    {
        serviceHost = new DataServiceHost(serviceToHost, new Uri[] { new Uri(ConfigurationManager.AppSettings["DataServiceHostAddress"]) });
    }

    public override void Before(System.Reflection.MethodInfo methodUnderTest)
    {
        try { serviceHost.Open(); }
        catch
        {
            try { serviceHost.Close(); }
            catch
            {
                try { serviceHost.Abort(); }
                catch { }
            }
        }
        base.Before(methodUnderTest);
    }

    public override void After(System.Reflection.MethodInfo methodUnderTest)
    {
        base.After(methodUnderTest);
        try { serviceHost.Close(); }
        catch
        {
            try { serviceHost.Abort(); }
            catch { }
        }
    }
}

Here is the data model class (separate project, referenced by all other projects):

public class DatabaseVersionDataModel
{
    private readonly List<DatabaseVersion> templist;
    public DatabaseVersionDataModel()
    {
        templist = new List<DatabaseVersion> { 
            new DatabaseVersion() { 
                MajorVersionId = 0, 
                MinorVersionId = 0, 
                BuildVersionId = 0, 
                VersionId = 1 } 
        };
        DatabaseVersions = templist.AsQueryable();
    }
    public IQueryable<DatabaseVersion> DatabaseVersions { get; private set; }
}

Here is the database version class also in model project:

[DataServiceKey("VersionId")]
public class DatabaseVersion
{
    public int VersionId { get; set; }
    public int MajorVersionId { get; set; }
    public int MinorVersionId { get; set; }
    public int BuildVersionId { get; set; }
}

Here is the DatabaseVersionService.svc file in my data services project (empty asp.net, compiles, debugs out of iisexpress and atom or json is browseable):

public class DatabaseVersionService : DataService<DatabaseVersionDataModel>
{
    // This method is called only once to initialize service-wide policies.
    public static void InitializeService(DataServiceConfiguration config)
    {
        // TODO: set rules to indicate which entity sets and service operations are visible, updatable, etc.
        // Examples:
        // config.SetEntitySetAccessRule("MyEntityset", EntitySetRights.AllRead);
        // config.SetServiceOperationAccessRule("MyServiceOperation", ServiceOperationRights.All);
        config.SetEntitySetAccessRule("*", EntitySetRights.AllRead);
        config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V3;
    }
}

Here is the output after removing throwingrecursionbehavior and adding omitonrecursionbehavior:

Result Message: System.InvalidCastException : Unable to cast object of type 'Ploeh.AutoFixture.Kernel.OmitSpecimen' to type 'skeletor.Domain.DatabaseVersion'. Result StackTrace:
at Ploeh.AutoFixture.Kernel.SpecimenFactory2.Create(Object request, ISpecimenContext context) at Ploeh.AutoFixture.Kernel.NoSpecimenOutputGuard.Create(Object request, ISpecimenContext context) at Ploeh.AutoFixture.Kernel.Postprocessor1.Create(Object request, ISpecimenContext context) at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.<>c_DisplayClass6.b_1(ISpecimenBuilder b) at System.Linq.Enumerable.WhereSelectListIterator2.MoveNext() at System.Linq.Enumerable.WhereSelectEnumerableIterator2.MoveNext() at System.Linq.Enumerable.d_a51.MoveNext() at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable1 source) at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context) at Ploeh.AutoFixture.Kernel.FilteringSpecimenBuilder.Create(Object request, ISpecimenContext context) at Ploeh.AutoFixture.Dsl.NodeComposer1.Create(Object request, ISpecimenContext context) at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.<>c__DisplayClass6.<Create>b__1(ISpecimenBuilder b) at System.Linq.Enumerable.WhereSelectListIterator2.MoveNext() at System.Linq.Enumerable.WhereSelectEnumerableIterator2.MoveNext() at System.Linq.Enumerable.<DefaultIfEmptyIterator>d__a51.MoveNext() at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable1 source) at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context) at Ploeh.AutoFixture.Kernel.RecursionGuard.Create(Object request, ISpecimenContext context) at Ploeh.AutoFixture.Kernel.RecursionGuard.Create(Object request, ISpecimenContext context) at Ploeh.AutoFixture.Dsl.CompositeNodeComposer1.Create(Object request, ISpecimenContext context) at Ploeh.AutoFixture.Kernel.SpecimenContext.Resolve(Object request) at Ploeh.AutoFixture.Kernel.SpecimenFactory2.Create(Object request, ISpecimenContext context) at Ploeh.AutoFixture.Kernel.NoSpecimenOutputGuard.Create(Object request, ISpecimenContext context) at Ploeh.AutoFixture.Kernel.Postprocessor1.Create(Object request, ISpecimenContext context) at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.<>c_DisplayClass6.b_1(ISpecimenBuilder b) at System.Linq.Enumerable.WhereSelectListIterator2.MoveNext() at System.Linq.Enumerable.WhereSelectEnumerableIterator2.MoveNext() at System.Linq.Enumerable.d_a51.MoveNext() at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable1 source) at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context) at Ploeh.AutoFixture.Kernel.FilteringSpecimenBuilder.Create(Object request, ISpecimenContext context) at Ploeh.AutoFixture.Dsl.NodeComposer1.Create(Object request, ISpecimenContext context) at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.<>c__DisplayClass6.<Create>b__1(ISpecimenBuilder b) at System.Linq.Enumerable.WhereSelectListIterator2.MoveNext() at System.Linq.Enumerable.WhereSelectEnumerableIterator2.MoveNext() at System.Linq.Enumerable.<DefaultIfEmptyIterator>d__a51.MoveNext() at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable1 source) at Ploeh.AutoFixture.Kernel.CompositeSpecimenBuilder.Create(Object request, ISpecimenContext context) at Ploeh.AutoFixture.Kernel.RecursionGuard.Create(Object request, ISpecimenContext context) at Ploeh.AutoFixture.Kernel.RecursionGuard.Create(Object request, ISpecimenContext context) at Ploeh.AutoFixture.Dsl.CompositeNodeComposer1.Create(Object request, ISpecimenContext context) at Ploeh.AutoFixture.Kernel.SpecimenContext.Resolve(Object request) at Ploeh.AutoFixture.SpecimenFactory.CreateAnonymous[T](ISpecimenContext context, T seed) at Ploeh.AutoFixture.SpecimenFactory.CreateAnonymous[T](ISpecimenContext context) at Ploeh.AutoFixture.SpecimenFactory.CreateAnonymous[T](ISpecimenBuilderComposer composer) at Ploeh.AutoFixture.SpecimenFactory.CreateAnonymous[T](IPostprocessComposer`1 composer) at skeletor.AcceptanceTests.InfrstructureTests.DataServiceGetsDatabaseVersion() in d:\projects\skeletor\skeletor.AcceptanceTests\InfrstructureTests.cs:line 31

Answer 1

Assuming that you use WCF Data Services 5.* for OData V3, you can try the following:

Supplying a custom Uri:

As with any other generated specimen, it is possible to completely take over it's creation. We can customize the creation of any Uri as follows:

public class CustomUriBuilder : ISpecimenBuilder
{
    public object Create(object request, ISpecimenContext context)
    {
        if (request == typeof(Uri))
        {
            return new Uri(
                ConfigurationManager.AppSettings["DataServiceHostAddress"]);
        }

        return new NoSpecimen(request);
    }
}

Using the above custom ISpecimenBuilder type, each time a Uri is requested, a predefined Uri will be returned.

Customizing the Fixture instance:

The test DataServiceGetsDatabaseVersion can now be rewritten:

[Fact]
[UseDataService(typeof(DatabaseVersionService))]
public void DataServiceGetsDatabaseVersion()
{
    var fixture = new Fixture();
    fixture.Customize<VersionClientProxy>(c => c.OmitAutoProperties());
    fixture.Customizations.Add(new CustomUriBuilder());
    fixture.Inject(
        new DatabaseVersion
        {
            MajorVersionId = 0,
            MinorVersionId = 0,
            BuildVersionId = 0,
            VersionId = 1
        });

    var sut = fixture.CreateAnonymous<VersionClientProxy>();
    var version = fixture.CreateAnonymous<DatabaseVersion>();
    var expected = version.AsSource().OfLikeness<DatabaseVersion>();

    var actual = (from a in sut.DatabaseVersions
                    orderby a.VersionId descending
                    select a).FirstOrDefault();

    Assert.True(expected.Equals(actual));
}

Hope that helps.