protected SortedMap<String, String> create(Entry<String, String>[] entries) {
                /*
                 * TODO(cpovirk): it would be nice to create an input Map and use
                 * the copy constructor here and in the other tests
                 */
                return populate(new TreeMap<String, String>(), entries);
              }
            })
        .named("TreeMap, natural")
        .withFeatures(

        // TODO currently this is first wins, but really we should take the latest by comparing either the
        // snapshot timestamp, or some other timestamp later encoded into the metadata.
        // TODO this needs to be repeated here so the merging doesn't interfere with the written metadata
        //  - we'd be much better having a pristine input, and an ongoing metadata for merging instead

   * This test checks an implementation dependent feature. It tests that the method {@code addEdge}
   * will silently add the missing nodes to the graph, then add the edge connecting them. We are not
   * using the proxy methods here as we want to test {@code addEdge} when the end-points are not
   * elements of the graph.
   */
  @Test
  public void addEdge_nodesNotInGraph() {
    assume().that(graphIsMutable()).isTrue();

   * This test checks an implementation dependent feature. It tests that the method {@code addEdge}
   * will silently add the missing nodes to the graph, then add the edge connecting them. We are not
   * using the proxy methods here as we want to test {@code addEdge} when the end-points are not
   * elements of the graph.
   */
  @Test
  public void addEdge_nodesNotInGraph() {
    assume().that(graphIsMutable()).isTrue();

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