Bug 15479 Add tests for ILS.pm

Bug 15479 Add tests for ILS.pm

This patch specifically adds a test for the sub added to
resolve Bug 15479. As no test script existed to add this two
added one which also tests that ILS objects can be instantiated
correctly and offer the required interface

NOTE: This does not apply without the first patch.
      Comment #3 suggested a unit test that would fail
      before and pass after. So while this code is good,
      it missed the before case. -- mtompset

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Brendan Gallagher brendan@bywatersolutions.com
(cherry picked from commit df4b1552211aae130b2ac31b44f45892c342e28c)
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>