In a postmodern world, it does not. It is a fiction. Ultimately, Hamp-Lyons cannot answer these questions. Different society, different ethics. It is not surprising that the moral problems of the late 20th Century have finally caught up with applied linguists and language testers.
Professionalism is to do with codes, contracts, training, and standards of practice.
These may develop and change over time, but the profession at any one time agrees that they will behave according to an agreed norm - irrespective of where you live, what nationality you are, or what kind of institution you work in. This lengthy document, published in 1995, is a review of the standards used and implemented by a range of tests in use throughout the world. This work was preparatory to drawing up a code of practice for the International Language Testing Association, which is work currently in progress. Another related area that has recently attracted a great deal of attention is that of accountability. These include the test takers, teachers, school administrators, community agencies, public officials and so on.