@Test
void testGraphNoEdges() {

  Node root = new Node.Builder().id("owl:Thing").label("root").type(Node.RDFTYPES.CLASS).build();
  List<Node> nodes = ImmutableList.of(root);
  Graph graph = new Graph.Builder().nodes(nodes).build();
  GraphDocument graphDocument = new GraphDocument.Builder().graphs(ImmutableList.of(graph)).build();
  assertThrows(PhenolRuntimeException.class, () -> OboGraphDocumentAdaptor.builder().build(graphDocument), "No edges found in loaded ontology.");
}