Bug 12876: Improve unit tests for CanReserveBeCanceledFromOpac

Bug 12876: Improve unit tests for CanReserveBeCanceledFromOpac

This patch fix the subroutine name and add a restriction on the
arguments: both argument are mandatory!

Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
Conflicts:
	t/db_dependent/Reserves.t

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
(cherry picked from commit ea2c5633cdd3e23c5ffd00aef206ab14372cb265)