patch 9.1.0792: tests: Test_set_values() is not comprehensive enough

Problem:  tests: Test_set_values() is not comprehensive enough
Solution: Add a lot more test cases (Milly)

closes: #15892

Signed-off-by: Milly <milly.ca@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

Author: Milly