Bug 27708: (QA follow-up) Add a few tests for Koha::Edifact::Order

Bug 27708: (QA follow-up) Add a few tests for Koha::Edifact::Order

1. This adds a simple regression test to make sure order_line() method
executes correctly with basket create_items set to "ordering" and
"receiving".

2. A simple test for the filename method is added

To test:
 1) prove t/db_dependent/Koha/Edifact/Order.t

Signed-off-by: Joonas Kylmälä <joonas.kylmala@iki.fi>
Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Petro Vashchuk <stalkernoid@gmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit 8c1ea4ec8ab6509c67538b1bf78cdf9e44d60c96)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>