public void MutateCatalog_ShouldThrowChangeRejectedException() { ExceptionAssert.Throws <ChangeRejectedException>(() => { var ctx = new RegistrationBuilder(); ctx.ForType <CFoo>().Export <IFoo>(); var typeCatalog = new TypeCatalog(Helpers.GetEnumerableOfTypes(typeof(CFoo)), ctx); Assert.IsTrue(typeCatalog.Parts.Count() != 0); var aggregateCatalog = new AggregateCatalog(); aggregateCatalog.Catalogs.Add(typeCatalog); var compositionService = aggregateCatalog.CreateCompositionService(); //Add it again aggregateCatalog.Catalogs.Add(typeCatalog); }); }