public void TestExceptions()
        {
            var executor = new EnvironmentBuilder(new Mock <IImplementationStore>(MockBehavior.Loose).Object);

            executor.Invoking(x => x.Inject(new Selections {
                Command = Command.NameRun
            }))
            .Should().Throw <ExecutorException>(because: "Selections with no implementations should be rejected");
            executor.Invoking(x => x.Inject(new Selections {
                Implementations = { new ImplementationSelection() }
            }))
            .Should().Throw <ExecutorException>(because: "Selections with no start command should be rejected");
        }
        private static void ExpectCommandException(Selections selections)
        {
            var storeMock = new Mock <IImplementationStore>(MockBehavior.Loose);

            storeMock.Setup(x => x.GetPath(It.IsAny <ManifestDigest>())).Returns("test path");
            var executor = new EnvironmentBuilder(storeMock.Object);

            executor.Invoking(x => x.Inject(selections))
            .Should().Throw <ExecutorException>(because: "Invalid Selections should be rejected");
        }