So today I was trying to get the following test to pass:

    [TestFixture]
    public class When_getting_a_step_property_value
    {
        [Test]
        public void a_value_set_can_be_retreived()
        {
            // Arrange
            var model = new FieldMappingModel { DateFormat = "test" };
 
            // Act
            var valueFound = new StepValueService().Get(x => x.DateFormat);
 
            // Assert
            Assert.AreEqual(model.DateFormat, valueFound);
        }
    }

Where the StepValueService looked like this:

    public class StepValueService
    {
        public dynamic Get(Expression<Func<dynamic, dynamic>> publicGetter)
        {
            var memberExpression = (MemberExpression)publicGetter.Body;
            var propertyName = memberExpression.Member.Name;
 
            // Doing some funky stuff with reflectoin using the properyName
            return null;
        }
     }

This wouldn't compile failing with the following error:

An expression tree may not contain a dynamic operation

Changing the service to the following fixed it but it was rather slow:

         public class StepValueService
         {
                 public dynamic Get(Func<dynamic, dynamic> publicGetter)
                 {
                          var propertyName = publicGetter(new DynamicMemberNameExpression());
 
                          // Doing some funky stuff with reflection using the properyName
                          return null;
                 }
 
                 private class DynamicMemberNameExpression : DynamicObject
                 {
                          public override bool TryGetMember(GetMemberBinder binder, out object result)
                          {
                                   result = binder.Name;
                                   return true;
                          }
                 }                
         }

Ended up not using this but might be interesting in the future...