ConfigurationGraphResolveState configuration = iter.next();
            if (configuration.getMetadata().getHierarchy().contains(toAdd.getName())) {
                // this configuration is a child of toAdd, so no need to add it
                return;
            }
            if (toAdd.getMetadata().getHierarchy().contains(configuration.getName())) {
                // toAdd is a child, so implies this configuration

        // hierarchy will not change anymore and all configurations in the hierarchy
        // will no longer be mutated.
        ImmutableSet<String> hierarchy = Configurations.getNames(configuration.getHierarchy());
        CalculatedValue<DefaultLocalConfigurationMetadata.ConfigurationDependencyMetadata> dependencies =

    private ConfigurationGraphResolveState config(name, visible) {
        def toConfig = Stub(ConfigurationGraphResolveMetadata)
        toConfig.isVisible() >> visible
        toConfig.name >> name
        toConfig.getHierarchy() >> ImmutableSet.of(name)
        def toState = Stub(ConfigurationGraphResolveState)
        toState.metadata >> toConfig
        toState.asVariant() >> { throw new RuntimeException() }
        return toState
    }