anchor.diff:          |> Seq.distinctBy (fun x -> x.Key)
           |> System.Collections.Concurrent.ConcurrentDictionary
   
  -    let langServices = TestHostLanguageServices(this, LanguageNames.FSharp)
  +    let langServices = TestHostLanguageServices(this, LanguageNames.FSharp, exportProvider)
   
       override _.Workspace = workspace
   
  
positive.code: type TestHostWorkspaceServices(hostServices: HostServices, workspace: Workspace) as this =
      inherit HostWorkspaceServices()
  
      let services1 =
          exportProvider.GetExports<IWorkspaceService, TestWorkspaceServiceMetadata>()
  
  
negative.code:         |> Seq.append MefHostServices.DefaultAssemblies
          |> Array.ofSeq
  
      let createExportProvider() =
          let resolver = Resolver.DefaultInstance
          let catalog = 
              let asms = getAssemblies()
  