Spec to demonstrate context + network call to get results for ldpath.rb issue #3

use_context_only_spec.rb

require 'spec_helper'
require 'byebug'

describe 'ldpath_program' do
  let(:program) { ldpath_program(ldpath) }
  let(:prefixes) do
    {
      "madsrdf" => "http://www.loc.gov/mads/rdf/v1#",
      "schema" => "http://www.w3.org/2000/01/rdf-schema#"
    }
  end

  let(:subject_uri) { RDF::URI('http://id.loc.gov/authorities/names/n79021164') }

  let(:graph) do
    graph = RDF::Graph.new
    graph << [subject_uri, RDF::Vocab::MADS.authoritativeLabel, 'Mark Twain']
    graph
  end

  let(:ldpath) { "madsrdf:authoritativeLabel :: xsd:string" }
  let(:expected_values) { ['Mark Twain'] }

  it 'returns values from context only' do
    # Test fails with actual_values: ["Mark Twain", "Twain, Mark, 1835-1910"]
    # The second value is retrieved by making a network request to the subject_uri.
    # IN LOG:  Loading "http://id.loc.gov/authorities/names/n79021164"
    # Is there a way to force ldpath to use the provided context only?
    expect(ldpath_evaluate(program, graph, subject_uri)).to eq expected_values
  end
end

def ldpath_program(ldpath)
  program_code = ""
  prefixes.each { |key, url| program_code << "@prefix #{key} : <#{url}> \;\n" }
  program_code << "property = #{ldpath} \;"
  Ldpath::Program.parse program_code
end

def ldpath_evaluate(program, graph, subject_uri)
  output = program.evaluate subject_uri, context: graph
  output.nil? ? nil : output['property'].uniq
end