tag.cs

    internal struct Tag
    {
        private readonly string name;
        private const string DEFAULT_TAG_NAME = "UnCategorized";

        public Tag(string name)
        {
            this.name = name;
        }

        public string Name
        {
            get { return name ?? DEFAULT_TAG_NAME; }
        }
    }

tag_tests.cs

    [Fact]
    public void default_Tag_should_have_Name_of_UnCategorized()
    {
        default(Tag).Name.ShouldEqual("UnCategorized");
        new Tag().Name.ShouldEqual("UnCategorized");
        Activator.CreateInstance<Tag>().Name.ShouldEqual("UnCategorized");
    }

    [Fact]
    public void list_of_tags_should_return_default()
    {
        var list = new List<Tag>();
        list.Count.ShouldEqual(0);

        var first = list.FirstOrDefault();
        first.Name.ShouldEqual("UnCategorized");
    }