[TestInitialize]
    public void Setup()
    {
        var unityContainer = A.Fake<IUnityContainer>();

        var addTagAction = A.Fake<IAddTagAction>();

        A.CallTo(() => unityContainer.Resolve(typeof(IAddTagAction), null, A<ResolverOverride[]>._)).Returns(addTagAction);

        this.testee = new ActionFactory(unityContainer);
    }

public interface IAddTagAction : IBaseAction
{
}

public interface IBaseAction
{
    void Execute(IList<long> artikelIds, int? id, RegelModel regelModel);
    string GetWertbezeichnung(int? wert);
    string GetWertbezeichnung(IList<int> werte);
}

public class AddTagAction : BaseAction, IAddTagAction
{
    public AddTagAction(
        IEfContextFactory efContextFactory,
        IRepositoryFactory repositoryFactory,
        IDateTimeProvider dateTimeProvider)
        : base(efContextFactory, repositoryFactory, dateTimeProvider)
    {
    }

    public override void Execute(IList<long> artikelIds, int? tagId, RegelModel regelModel)
    {
        // ...
    }

    /// <inheritdoc />
    public override string GetWertbezeichnung(IList<int> werte)
    {
        using (var context = this.EfContextFactory.Create(RequestInfo))
        {
            var tagRepository = this.RepositoryFactory.Create<ITagRepository>(context, RequestInfo);
            var tags = tagRepository.GetTagNames(werte.ToList()).FirstOrDefault();
            return tags.Value;
        }
    }

public abstract class BaseAction : IBaseAction
{
    protected BaseAction(IEfContextFactory efContextFactory, IRepositoryFactory repositoryFactory, IDateTimeProvider dateTimeProvider)
    {
        this.EfContextFactory = efContextFactory;
        this.RepositoryFactory = repositoryFactory;
        this.DateTimeProvider = dateTimeProvider;
    }

    protected IRepositoryFactory RepositoryFactory { get; }

    protected IEfContextFactory EfContextFactory { get; }

    protected IDateTimeProvider DateTimeProvider { get; }

    public virtual void Execute(IList<long> artikelIds, int? id, RegelModel regelModel)
    {
        // ...
    }

    public string GetWertbezeichnung(int? wert)
    {
        if (!wert.HasValue) {
            return string.Empty;
        }
        var werte = new List<int> { wert.Value };
        return GetWertbezeichnung(werte);
    }

    public abstract string GetWertbezeichnung(IList<int> werte);
}