ExceptionThrowingPackageRepository AddFailingPackageRepository (Exception exception)
		{
			var repository = new ExceptionThrowingPackageRepository {
				GetPackagesException = exception
			};
			repositories.Add (repository);
			return repository;
		}
		public void ReadPackages_ActivePackageSourceIsAggregatePackageRepositoryWithOneFailingRepository_RepositoryErrorIsDisplayed ()
		{
			CreateRegisteredPackageRepositories ();
			var repository = new ExceptionThrowingPackageRepository (new Exception ("Error1"));
			AddAggregateRepository (new FakePackageRepository (), repository);
			CreateViewModel (registeredPackageRepositories);

			viewModel.ReadPackages ();
			CompleteReadPackagesTask ();

			Assert.IsTrue (viewModel.HasError);
			Assert.That (viewModel.ErrorMessage, Contains.Substring ("Error1"));
		}