Test Driven Validation Logic with Extract & Override

gistfile1.cs

  public class Dinner
    {
        public string Description { get; set; }
        public string Title { get; set; }
        public DateTime EventDate { get; set; }

        public bool IsValid { get { return validate(); }}

        private bool validate()
        {
            return validateTitle() 
                && validateDescription() 
                && validateEventDate();
        }

        protected virtual bool validateTitle()
        {
            return Title.Length>3;
        }
        protected virtual bool validateDescription()
        {
            return false;
        }
        protected virtual bool validateEventDate()
        {
            return false;
        }
    }

    [TestFixture]
    public class DinnerTests
    {
        [Test]
        public void IsValid_TitleLessThan4Chars_ReturnsFalse()
        {
            TestableDinner dinner = new TestableDinner
                                        {
                                            Title = "123", 
                                            DescriptionShould = true, 
                                            EventDateShould = true
                                        };

            Assert.IsFalse(dinner.IsValid);
        }
        
        [Test]
        public void IsValid_TitleMoreThan3Chars_ReturnsTrue()
        {
            TestableDinner dinner = new TestableDinner
                                        {
                                            Title = "1234", 
                                            DescriptionShould = true, 
                                            EventDateShould = true
                                        };

            Assert.IsTrue(dinner.IsValid);
        }
    }

    public class TestableDinner : Dinner
    {
        public bool? DescriptionShould;
        public bool? TitleShould;
        public bool? EventDateShould;

        protected override bool validateTitle()
        {
            if (TitleShould!=null)
                return TitleShould.Value;
            return base.validateTitle();
        }

        protected override bool validateDescription()
        {
            if (DescriptionShould!= null)
                return DescriptionShould.Value;
            return base.validateDescription();
        }

        protected override bool validateEventDate()
        {
            if (EventDateShould != null)
                return EventDateShould.Value;
            return base.validateEventDate();
        }
    }