Bug 30731: Unit tests

Bug 30731: Unit tests

Installer_pm.t can safely be discarded, having Installer_PerlModules.t.

Note: Without the second patch, the test about versions_info being silent
might fail. With the second patch, it should pass.
Note that since the order of requiring the cpan modules varies (without
the second patch), the results (potential warnings) vary too.

Test plan:
Run t/Installer_PerlModules.t

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit 2265739a378c1d31c5ea3d4beb07cbaa4d04e62b)

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
(cherry picked from commit 39e250a6f3d3e1bdf0fa1c00359a4823b77b5083)
Signed-off-by: Arthur Suzuki <arthur.suzuki@biblibre.com>