@SteveCrow I work in an Agile environment and the important thing to remember is that UX and Testing do not need to held until the entire product is completed. We generally have UX Requirements Tasks that apply at the beginning of any new functional capabilities and then UX Validation Tasks that fall at the end of new functional capabilities. The goal here is to make certain that we begin by figuring out what we want to do and then end by validating that we've created what we set out to create.
Additionally, it sounded like you were saying that Testing and UX are the same thing which is not inherently so. There is such a thing as UX Testing which is intended to provide feedback on quality but Technical Testing is definitely a separate task in our group and is used to make certain that the solution actually functions properly in all the situations it shoud.
Rules probably shift some based on the size and shape of your team but that's how we do it at IntelliDyne, LLC.