Intentar ejecutar un error en la implementación de mi datacontext de EF que produce un error bastante críptico.

Test Name:  Nodes_can_be_saved
Test FullName:  MyProj.Test.Integration.AFDataContextTest.Nodes_can_be_saved
Test Source:    c:\Users\pvencill. \Documents\Visual Studio 2012\Projects\MyProj\MyProj.Test\Integration\AFDataContextTest.cs : line 49
Test Outcome:   Failed
Test Duration:  0:00:01.4192808

Result Message: 
Test method MyProj.Test.Integration.AFDataContextTest.Nodes_can_be_saved threw exception: 
System.Data.Entity.Infrastructure.DbUpdateException: Error retrieving values from ObjectStateEntry. See inner exception for details. ---> System.Data.UpdateException: Error retrieving values from ObjectStateEntry. See inner exception for details. ---> System.Collections.Generic.KeyNotFoundException: The given key was not present in the dictionary.
Result StackTrace:  
at System.Collections.Generic.Dictionary`2.get_Item(TKey key)
   at System.Data.Mapping.ViewGeneration.Structures.MemberDomainMap.GetDomainInternal(MemberPath path)
   at System.Data.Mapping.ViewGeneration.QueryRewriting.FragmentQueryKB.CreateIsOfTypeCondition(MemberPath currentPath, IEnumerable`1 derivedTypes, MemberDomainMap domainMap)
   at System.Data.Mapping.ViewGeneration.QueryRewriting.FragmentQueryKB.CreateVariableConstraintsRecursion(EdmType edmType, MemberPath currentPath, MemberDomainMap domainMap, EdmItemCollection edmItemCollection)
   at System.Data.Mapping.ViewGeneration.QueryRewriting.FragmentQueryKB.CreateVariableConstraintsRecursion(EdmType edmType, MemberPath currentPath, MemberDomainMap domainMap, EdmItemCollection edmItemCollection)
   at System.Data.Mapping.ViewGeneration.ViewgenContext..ctor(ViewTarget viewTarget, EntitySetBase extent, IEnumerable`1 extentCells, CqlIdentifiers identifiers, ConfigViewGenerator config, MemberDomainMap queryDomainMap, MemberDomainMap updateDomainMap, StorageEntityContainerMapping entityContainerMapping)
   at System.Data.Mapping.ViewGeneration.ViewGenerator.CreateViewgenContext(EntitySetBase extent, ViewTarget viewTarget, CqlIdentifiers identifiers)
   at System.Data.Mapping.ViewGeneration.ViewGenerator.GenerateDirectionalViewsForExtent(ViewTarget viewTarget, EntitySetBase extent, CqlIdentifiers identifiers, KeyToListMap`2 views)
   at System.Data.Mapping.ViewGeneration.ViewGenerator.GenerateDirectionalViews(ViewTarget viewTarget, CqlIdentifiers identifiers, KeyToListMap`2 views)
   at System.Data.Mapping.ViewGeneration.ViewGenerator.GenerateAllBidirectionalViews(KeyToListMap`2 views, CqlIdentifiers identifiers)
   at System.Data.Mapping.ViewGeneration.ViewgenGatekeeper.GenerateViewsFromCells(List`1 cells, ConfigViewGenerator config, CqlIdentifiers identifiers, StorageEntityContainerMapping containerMapping)
   at System.Data.Mapping.ViewGeneration.ViewgenGatekeeper.GenerateViewsFromMapping(StorageEntityContainerMapping containerMapping, ConfigViewGenerator config)
   at System.Data.Mapping.StorageMappingItemCollection.ViewDictionary.SerializedGenerateViews(StorageEntityContainerMapping entityContainerMap, Dictionary`2 resultDictionary)
   at System.Data.Mapping.StorageMappingItemCollection.ViewDictionary.SerializedGetGeneratedViews(EntityContainer container)
   at System.Data.Common.Utils.Memoizer`2.<>c__DisplayClass2.<Evaluate>b__0()
   at System.Data.Common.Utils.Memoizer`2.Result.GetValue()
   at System.Data.Common.Utils.Memoizer`2.Evaluate(TArg arg)
   at System.Data.Mapping.StorageMappingItemCollection.ViewDictionary.GetGeneratedView(EntitySetBase extent, MetadataWorkspace workspace, StorageMappingItemCollection storageMappingItemCollection)
   at System.Data.Mapping.Update.Internal.ViewLoader.InitializeEntitySet(EntitySetBase entitySetBase, MetadataWorkspace workspace)
   at System.Data.Mapping.Update.Internal.ViewLoader.SyncInitializeEntitySet[TArg,TResult](EntitySetBase entitySetBase, MetadataWorkspace workspace, Func`2 evaluate, TArg arg)
   at System.Data.Mapping.Update.Internal.ViewLoader.SyncContains[T_Element](EntitySetBase entitySetBase, MetadataWorkspace workspace, Set`1 set, T_Element element)
   at System.Data.Mapping.Update.Internal.ExtractorMetadata..ctor(EntitySetBase entitySetBase, StructuralType type, UpdateTranslator translator)
   at System.Data.Mapping.Update.Internal.UpdateTranslator.GetExtractorMetadata(EntitySetBase entitySetBase, StructuralType type)
   at System.Data.Mapping.Update.Internal.ExtractorMetadata.ExtractResultFromRecord(IEntityStateEntry stateEntry, Boolean isModified, IExtendedDataRecord record, Boolean useCurrentValues, UpdateTranslator translator, ModifiedPropertiesBehavior modifiedPropertiesBehavior)
   at System.Data.Mapping.Update.Internal.RecordConverter.ConvertStateEntryToPropagatorResult(IEntityStateEntry stateEntry, Boolean useCurrentValues, ModifiedPropertiesBehavior modifiedPropertiesBehavior)
 --- End of inner exception stack trace ---
    at System.Data.Mapping.Update.Internal.RecordConverter.ConvertStateEntryToPropagatorResult(IEntityStateEntry stateEntry, Boolean useCurrentValues, ModifiedPropertiesBehavior modifiedPropertiesBehavior)
   at System.Data.Mapping.Update.Internal.ExtractedStateEntry..ctor(UpdateTranslator translator, IEntityStateEntry stateEntry)
   at System.Data.Mapping.Update.Internal.UpdateTranslator.LoadStateEntry(IEntityStateEntry stateEntry)
   at System.Data.Mapping.Update.Internal.UpdateTranslator.PullModifiedEntriesFromStateManager()
   at System.Data.Mapping.Update.Internal.UpdateTranslator.ProduceCommands()
   at System.Data.Mapping.Update.Internal.UpdateTranslator.Update(IEntityStateManager stateManager, IEntityAdapter adapter)
   at System.Data.EntityClient.EntityAdapter.Update(IEntityStateManager entityCache)
   at System.Data.Objects.ObjectContext.SaveChanges(SaveOptions options)
   at System.Data.Entity.Internal.InternalContext.SaveChanges()
 --- End of inner exception stack trace ---
    at System.Data.Entity.Internal.InternalContext.SaveChanges()
   at System.Data.Entity.Internal.LazyInternalContext.SaveChanges()
   at System.Data.Entity.DbContext.SaveChanges()
   at MyProj.Data.MyProjDataContext.SaveChanges() in c:\Users\pvencill. \Documents\Visual Studio 2012\Projects\MyProj\MyProj.Data\MyProjDataContext.cs:line 44
   at MyProj.Test.Integration.AFDataContextTest.Nodes_can_be_saved() in c:\Users\pvencill. \Documents\Visual Studio 2012\Projects\MyProj\MyProj.Test\Integration\AFDataContextTest.cs:line 55

La investigación del error dio lugar a pocos resultados en Google, pero los que encontré sugirieron que es algo que hacer con mis relaciones modelo, aunque al analizar el DB que generaron las migraciones, todo parece en orden a mis ojos. Mis modelos relevantes son los siguientes:

Mis contextos de datos DBSets y modelCreating definition:

public DbSet<Blip> Blips { get; set; }
        public DbSet<SensorAdapter> Sensors { get; set; }
        public DbSet<NodeReport> NodeReports { get; set; }
        public DbSet<Node> Nodes { get; set; }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Entity<Blip>().Property(b => b.TimeStamp).HasColumnType("datetime2");
            modelBuilder.Entity<Node>().HasMany<NodeReport>(n => n.NodeReports).WithRequired(nr=>nr.Node);
            modelBuilder.Entity<Blip>().HasMany<NodeReport>(b => b.NodeReports);

            base.OnModelCreating(modelBuilder);
        }

Los objetos Blips y SensorAdapter funcionaron bien antes de agregar NodeReports a ellos, así que sospecho que ahí está el proyecto.

Tengo un objeto Entidad base del que se heredan todas mis cosas, que solo define una propiedad de Id de tipo T; que funcionaba bien

NodeReport hereda de Report, cuya definición está aquí:

public abstract class Report : Entity<long>
    {
        public Report()
        {
            Status = Status.Unknown;
        }

        public DateTime TimeStamp { get; set; }
        public Status Status { get; set; }
        public String Raw { get; set; }
    }

NodeReport a su vez se define así:

public class NodeReport : Report
    {
        public virtual Node Node { get; set; }
        //public virtual Blip Blip { get; set; }
    }

Lo intenté con y sin el Blip, comenté en el momento mientras trato de reducir el problema.

Un nodo es también una clase bastante dispersa en el momento:

public class Node : Entity<long>
    {
        public Node ()
        {
                       NodeReports = new List<NodeReport>();
        }

        public String HostName { get;set; }
        public String Description { get; set; }
            public virtual IList<NodeReport> NodeReports { get; set; }
    }

Cualquier sugerencia sería muy apreciada, me he estado golpeando tratando de entenderlo.