}

  @Test
  public void forGraph_breadthFirst_diamond() {
    Traverser<Character> traverser = Traverser.forGraph(DIAMOND_GRAPH);
    assertEqualCharNodes(traverser.breadthFirst('a'), "abcd");
    assertEqualCharNodes(traverser.breadthFirst('b'), "bd");
    assertEqualCharNodes(traverser.breadthFirst('c'), "cd");
    assertEqualCharNodes(traverser.breadthFirst('d'), "d");
  }

  @Test

  public void testFileTraverser_emptyDirectory() throws Exception {
    assertThat(Files.fileTraverser().breadthFirst(rootDir)).containsExactly(rootDir);
  }

  public void testFileTraverser_nonExistingFile() throws Exception {
    File file = new File(rootDir, "file-that-doesnt-exist");

    assertThat(Files.fileTraverser().breadthFirst(file)).containsExactly(file);
  }

  public void testFileTraverser_file() throws Exception {

  public void testFileTraverser_emptyDirectory() throws Exception {
    assertThat(Files.fileTraverser().breadthFirst(rootDir)).containsExactly(rootDir);
  }

  public void testFileTraverser_nonExistingFile() throws Exception {
    File file = new File(rootDir, "file-that-doesnt-exist");

    assertThat(Files.fileTraverser().breadthFirst(file)).containsExactly(file);
  }

  public void testFileTraverser_file() throws Exception {

  public void testFileTraverser_emptyDirectory() throws Exception {
    assertThat(MoreFiles.fileTraverser().breadthFirst(rootDir)).containsExactly(rootDir);
  }

  public void testFileTraverser_nonExistingFile() throws Exception {
    Path file = rootDir.resolve("file-that-doesnt-exist");

    assertThat(MoreFiles.fileTraverser().breadthFirst(file)).containsExactly(file);
  }

  public void testFileTraverser_file() throws Exception {

  }

  @Test
  public void forGraph_breadthFirst_diamond() {
    Traverser<Character> traverser = Traverser.forGraph(DIAMOND_GRAPH);
    assertEqualCharNodes(traverser.breadthFirst('a'), "abcd");
    assertEqualCharNodes(traverser.breadthFirst('b'), "bd");
    assertEqualCharNodes(traverser.breadthFirst('c'), "cd");
    assertEqualCharNodes(traverser.breadthFirst('d'), "d");
  }

  @Test

   * Iterables.limit(Traverser.forGraph(graph).breadthFirst(node), maxNumberOfNodes);
   * }</pre>
   *
   * <p>See <a href="https://en.wikipedia.org/wiki/Breadth-first_search">Wikipedia</a> for more
   * info.
   *
   * @throws IllegalArgumentException if {@code startNode} is not an element of the graph
   */
  public final Iterable<N> breadthFirst(N startNode) {
    return breadthFirst(ImmutableSet.of(startNode));
  }

  /**

   * is in progress or when the iterators generated by {@link #children} are advanced.
   *
   * @deprecated Use {@link com.google.common.graph.Traverser#breadthFirst} instead, which has the
   *     same behavior.
   */
  @Deprecated
  public final FluentIterable<T> breadthFirstTraversal(final T root) {
    checkNotNull(root);
    return new FluentIterable<T>() {

   */
  public static <N> ImmutableSet<N> reachableNodes(Graph<N> graph, N node) {
    checkArgument(graph.nodes().contains(node), NODE_NOT_IN_GRAPH, node);
    return ImmutableSet.copyOf(Traverser.forGraph(graph).breadthFirst(node));
  }

  // Graph mutation methods

  // Graph view methods

  /**
   * Returns a view of {@code graph} with the direction (if any) of every edge reversed. All other