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  public abstract class TesterBase
  {
    public virtual void NullArgumentShouldThrow<TIn, TOut>(Func<TIn, TOut> function)
    {
      if (typeof(TIn).IsClass)
      {
        Assert.ThrowsException<ArgumentNullException>(() => function(default(TIn)), "Should throw ArgumentNullException");
      }
    }
  }

  public abstract class IBuilderTesterBase<TBuilder, TIn, TOut> : TesterBase where TBuilder : IBuilder<TIn, TOut>
  {
    protected abstract TBuilder Create();

    [TestMethod]
    public void TestBuildArgumentNullException()
    {
      var builder = Create();
      NullArgumentShouldThrow<TIn, TOut>(builder.Build);
    }

    // TODO: Other common IBuilder Tests
  }

  public abstract class SimpleIBuilderTesterBase<TBuilder, TIn, TOut> : IBuilderTesterBase<TBuilder, TIn, TOut> where TBuilder : IBuilder<TIn, TOut>, new()
  {
    protected override TBuilder Create()
    {
      return new TBuilder();
    }
  }

  public abstract class ComplexIBuilderTesterBase<TBuilder, TIn, TOut> : IBuilderTesterBase<TBuilder, TIn, TOut> where TBuilder : IBuilder<TIn, TOut>
  {
    Func<TBuilder> m_creator;

    public ComplexIBuilderTesterBase(Func<TBuilder> creator)
    {
      m_creator = creator;
    }

    protected override TBuilder Create()
    {
      return m_creator();
    }
  }

  [TestClass]
  public class ObjectBuilderTester : SimpleIBuilderTesterBase<ReferenceTypeBuilder, object, int>
  {
    // TODO: Other ObjectBuilder tests
  }

  [TestClass]
  public class DateTimeBuilderTester : SimpleIBuilderTesterBase<ValueTypeBuilder, DateTime, int>
  {
    // TODO: Other DateTimeBuilder tests
  }

  [TestClass]
  public class ComplexBuilderTester : ComplexIBuilderTesterBase<ComplexBuilder, object, int>
  {
    public ComplexBuilderTester() : base(DoCreate)
    {

    }

    private static ComplexBuilder DoCreate()
    {
      return new ComplexBuilder(null);
    }

    // TODO: Other ComplexBuilder tests
  }

  public abstract class TesterBase
  {
    protected bool IsNullableType(Type type)
    {
      return Nullable.GetUnderlyingType(type) != null;
    }

    public virtual void NullArgumentShouldThrow<TIn, TOut>(Func<TIn, TOut> function)
    {
      if (typeof(TIn).IsClass || IsNullableType(typeof(TIn)))
      {
        Assert.ThrowsException<ArgumentNullException>(() => function(default(TIn)), "Should throw ArgumentNullException");
      }
    }
  }

  public abstract class IBuilderTesterBase<TBuilder, TIn, TOut> : TesterBase where TBuilder : IBuilder<TIn, TOut>
  {
    protected abstract TBuilder Create();

    [TestMethod]
    public void TestBuildArgumentNullException()
    {
      var builder = Create();
      NullArgumentShouldThrow<TIn, TOut>(builder.Build);
    }

    // TODO: Other common IBuilder Tests
  }

  public abstract class SimpleIBuilderTesterBase<TBuilder, TIn, TOut> : IBuilderTesterBase<TBuilder, TIn, TOut> where TBuilder : IBuilder<TIn, TOut>, new()
  {
    protected override TBuilder Create()
    {
      return new TBuilder();
    }
  }

  public abstract class ComplexIBuilderTesterBase<TBuilder, TIn, TOut> : IBuilderTesterBase<TBuilder, TIn, TOut> where TBuilder : IBuilder<TIn, TOut>
  {
    Func<TBuilder> m_creator;

    public ComplexIBuilderTesterBase(Func<TBuilder> creator)
    {
      m_creator = creator;
    }

    protected override TBuilder Create()
    {
      return m_creator();
    }
  }

  [TestClass]
  public class ObjectBuilderTester : SimpleIBuilderTesterBase<ReferenceTypeBuilder, object, int>
  {
    // TODO: Other ObjectBuilder tests
  }

  [TestClass]
  public class DateTimeBuilderTester : SimpleIBuilderTesterBase<ValueTypeBuilder, DateTime, int>
  {
    // TODO: Other DateTimeBuilder tests
  }

  [TestClass]
  public class ComplexBuilderTester : ComplexIBuilderTesterBase<ComplexBuilder, object, int>
  {
    public ComplexBuilderTester() : base(DoCreate)
    {

    }

    private static ComplexBuilder DoCreate()
    {
      return new ComplexBuilder(null);
    }

    // TODO: Other ComplexBuilder tests
  }

Some explanation and thoughts about the above in order to answer the questions julealgon asks in the comment:

1. The idea of the TesterBase.NullArgumentShouldThrow(...) is, that it can be used by other tests. In fact the idea of TesterBase is that it should server as the owner of reusable "low level"/general purpose tests, that can be called by sub classes. It could have been implemented as a static helper class as well.

2. I think it's OK, that a test of null argument on a value type is bypassed without notice, because the test is irrelevant for those types. But you may have an other opinion about that.

3. In general IMO you should not be concerned about the depth of a class hierarchy as long as each level (subclass) serves a well defined purpose and is logical.

But again my answer is not postulating to be better than the approach of OP or even good. I were just trying to dive in to the field of the problem and understand it.

In an attempt to try to understand what you want to achieve, I came up with the below. Don't consider it as a review to make your code better - but just as an attempt to think along the paths of yours and t3chb0ts:

  public abstract class TesterBase
  {
    public virtual void NullArgumentShouldThrow<TIn, TOut>(Func<TIn, TOut> function)
    {
      if (typeof(TIn).IsClass)
      {
        Assert.ThrowsException<ArgumentNullException>(() => function(default(TIn)), "Should throw ArgumentNullException");
      }
    }
  }

  public abstract class IBuilderTesterBase<TBuilder, TIn, TOut> : TesterBase where TBuilder: IBuilder<TIn, TOut>, new()
  {
    protected TBuilder Create() => new TBuilder();

    [TestMethod]
    public void TestBuildArgumentNullException()
    {
      var builder = Create();
      NullArgumentShouldThrow<TIn, TOut>(builder.Build);
    }

    // TODO: Other common IBuilder Tests
  }

  [TestClass]
  public class ObjectBuilderTester : IBuilderTesterBase<ReferenceTypeBuilder, object, int>
  {
    // TODO: Other ObjectBuilder tests
  }

  [TestClass]
  public class DateTimeBuilderTester : IBuilderTesterBase<ValueTypeBuilder, DateTime, int>
  {
    // TODO: Other DateTimeBuilder tests
  }

In an attempt to try to understand what you want to achieve, I came up with the below. Don't consider it as a review to make your code better - but just as an attempt to think along the paths of yours and t3chb0ts:

  public abstract class TesterBase
  {
    public virtual void NullArgumentShouldThrow<TIn, TOut>(Func<TIn, TOut> function)
    {
      if (typeof(TIn).IsClass)
      {
        Assert.ThrowsException<ArgumentNullException>(() => function(default(TIn)), "Should throw ArgumentNullException");
      }
    }
  }

  public abstract class IBuilderTesterBase<TBuilder, TIn, TOut> : TesterBase where TBuilder : IBuilder<TIn, TOut>
  {
    protected abstract TBuilder Create();

    [TestMethod]
    public void TestBuildArgumentNullException()
    {
      var builder = Create();
      NullArgumentShouldThrow<TIn, TOut>(builder.Build);
    }

    // TODO: Other common IBuilder Tests
  }

  public abstract class SimpleIBuilderTesterBase<TBuilder, TIn, TOut> : IBuilderTesterBase<TBuilder, TIn, TOut> where TBuilder : IBuilder<TIn, TOut>, new()
  {
    protected override TBuilder Create()
    {
      return new TBuilder();
    }
  }

  public abstract class ComplexIBuilderTesterBase<TBuilder, TIn, TOut> : IBuilderTesterBase<TBuilder, TIn, TOut> where TBuilder : IBuilder<TIn, TOut>
  {
    Func<TBuilder> m_creator;

    public ComplexIBuilderTesterBase(Func<TBuilder> creator)
    {
      m_creator = creator;
    }

    protected override TBuilder Create()
    {
      return m_creator();
    }
  }

  [TestClass]
  public class ObjectBuilderTester : SimpleIBuilderTesterBase<ReferenceTypeBuilder, object, int>
  {
    // TODO: Other ObjectBuilder tests
  }

  [TestClass]
  public class DateTimeBuilderTester : SimpleIBuilderTesterBase<ValueTypeBuilder, DateTime, int>
  {
    // TODO: Other DateTimeBuilder tests
  } 

  [TestClass]
  public class ComplexBuilderTester : ComplexIBuilderTesterBase<ComplexBuilder, object, int>
  {
    public ComplexBuilderTester() : base(DoCreate)
    {

    }

    private static ComplexBuilder DoCreate()
    {
      return new ComplexBuilder(null);
    }

    // TODO: Other ComplexBuilder tests
  }

I admit that it maybe doesn't add any clarity to the picture, but I think it gets the job done.