This is what is currently quoted in LASORS with regards to the training flight:
The FI should make the purpose of the training flight
clear at the outset. His function is to ascertain the
applicant’s knowledge and skills, and interject if
necessary to improve on these. If the primary purpose
of the flight was for some other training then the FI must
select suitable items of general handling to fulfil the
purpose of the JAR-FCL requirement and brief how
these will fit into the profile for the purpose of the
applicant’s revalidation request.
Where the aim is achieved the FI will sign the
applicants logbook, append his/her licence number and
identify the ‘Training Flight’ for the examiners purpose.
We know this is not a test situation, but the final paragraph would seem to suggest that the FI can refuse to sign if the pilot was not to a standard (s)he deems safe.