Durable spec wrong and useless

[gkellogg]

RDF::Durable spec "is_expected.to save contents between instantiations" can't work if TRIPLES_FILE contains BNodes, as it will insert new statements where those BNodes are present. Secondly, it is not really testing durability; this would require something else where the repo was updated, and a new repo using the same endpoint was created which should now be the same. This probably relies on the uri argument identifying the endpoint, and/or a callout to do this. It might be something like the following:

if subject.durable?
  subject.empty!
  instance = subject.class.new(uri: subject.uri, subject.options)
  expect(subject).to be_empty
end