For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:inescid:grid/openSUSE_Tumbleweed/home:inescid:grid.repo
zypper refresh
zypper install python-zope.testing
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:inescid:grid/15.6/home:inescid:grid.repo
zypper refresh
zypper install python-zope.testing
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:inescid:grid/15.5/home:inescid:grid.repo
zypper refresh
zypper install python-zope.testing