Tests for how we handle parameters of different types

Consistency is certainly enticing (and was my original suggestion). Continuing down that path, using the full cast from string to targetType would be the ideal, right? I think we just want to make sure we're not in a situation where one path truncates and one throws an error (or something else).

To directly answer the question. is `byte[]` the only "interesting" type here? The problem with that in ValueSources was there were other objects that didn't have a nice to string, like ByteSource and BigDecimalWrapper.