Improve tests

[gkellogg]

From #10 (comment), more shared tests to check Repository conformance, and the set up to run tests on commit through the GitHub Actions CI task.

[stuzart]

I've made a little start on this on branch, adding the Virtuoso docker service, and a basic test that it is interacting an doing a query. These tests will fail unless the service is available, so I was thinking of checking if an environment variable is set, and otherwise skip (perhaps github sets one?)

I tried adding it_behaves_like "an RDF::Repository" which leads to a lot of errors, but many of which seem to stem from the same place

Failure/Error:
               @statements.each do |st|
                 if st.graph_name.equal?(DEFAULT_GRAPH)
                   st = st.dup
                   st.graph_name = nil
                 end

                 yield st

       NoMethodError:
         undefined method `each' for nil:NilClass
       Shared Example Group: "an RDF::Enumerable" called from /usr/share/rvm/gems/ruby-2.6.6/bundler/gems/rdf-spec-4fe4eb8a3288/lib/rdf/spec/dataset.rb:26
       Shared Example Group: "an RDF::Dataset" called from /usr/share/rvm/gems/ruby-2.6.6/bundler/gems/rdf-spec-4fe4eb8a3288/lib/rdf/spec/repository.rb:23

[gkellogg]

It's reasonable for tests to be be conditioned on an environment variable. See, for example, the postgres spec in the otherwise rather obsolete rdf-do gem.

This environment variable can be specified in the .github/workflows/ci.yml file along with starting up the docker image. General documentation for running the specs on the desktop would be useful, too.

It's not too surprising that the it_behaves_like "an RDF::Repository" fails, as the gem predates many of those conventions, so may need some TLC to bring into conformance.

This typically needs some instance variables set up to allow it to work properly. For example:

  # @see lib/rdf/spec/repository.rb in RDF-spec
  it_behaves_like "an RDF::Repository" do
    let(:repository) {@repository}
  end

Where @repository is an instance RDF::Virtuoso::Repository.

Also see rdf-mongo spec.