AutoMapperIssue.cs

public class ObjectUnderTest
{
    private string _prefix;

    public ObjectUnderTest(string prefix)
    {
       _prefix = prefix;
    }

    public dto MapObject(obj input)
    {
        AutoMapper.Mapper.CreateMap<obj, dto>()
        .ForMember(x => x.name, y => _prefix + y.name);
    }
}

public class TestClass
{
    public void Test1()
    {
        var test = new ObjectUnderTest(null);
        var testdto = test.MapObject(someTestObject);
    }
    public void Test2()
    {
        var test = new ObjectUnderTest("Hello ");
        var testdto = test.MapObject(someTestObject);
    }
}

I'd run from that static method AutoMapper call. :)