[Fact]
public void collection_types_are_all_possible_by_default()
{
    // NOTE that we do NOT make any explicit registration of
    // IList<IWidget>, IEnumerable<IWidget>, ICollection<IWidget>, or IWidget[]
    var container = new Container(_ =>
    {
        _.For<IWidget>().Add<AWidget>();
        _.For<IWidget>().Add<BWidget>();
        _.For<IWidget>().Add<CWidget>();
    });

    // ICollection<T> <-- Does not validate
    container.GetInstance<ICollection<IWidget>>()
        .Select(x => x.GetType())
        .ShouldHaveTheSameElementsAs(typeof(AWidget), typeof(BWidget), typeof(CWidget));
}