sharemessage-8.x-1.x-dev/tests/modules/sharemessage_test/sharemessage_test.routing.yml

sharemessage_test.view:
  path: '/sharemessage-test/{sharemessage}/{view_mode}'
  defaults:
    view_mode: 'full'
    _entity_view: 'sharemessage'
  requirements:
    _entity_access: 'sharemessage.view'