Well, I remember many fellow ppruners accusing Boeing and its subcontractors to simplify many of their tests too much, missing to simulate real in-service conditions...
Yeah, rather completely different subject.
Boeing (like any other aircraft manufacturer) did exactly what tests were required for the certification of their 787, if you try to blame someone for "simplifying tests" blame FAA. Certainly such tests do not require it simulate ELT fires. But if British (or any other) aviation agency wants to be satisfied as to completeness of this ELT accident investigation they
could attempt to do full scale tests which would include portions of the fuselage.