@Test
  @SuppressWarnings("CheckReturnValue")
  public void forTree_acceptsDirectedGraph() throws Exception {
    MutableGraph<String> graph = GraphBuilder.directed().build();
    graph.putEdge("a", "b");

    Traverser.forTree(graph); // Does not throw
  }

  @Test
  public void forTree_withUndirectedGraph_throws() throws Exception {
    MutableGraph<String> graph = GraphBuilder.undirected().build();

      throws IOException {
    testStreamingEncodes(encoding, decoded, encoded);
    testStreamingDecodes(encoding, encoded, decoded);
  }

  @GwtIncompatible // Writer
  private static void testStreamingEncodes(BaseEncoding encoding, String decoded, String encoded)
      throws IOException {
    StringWriter writer = new StringWriter();

        }

        @Override
        public void write(int b) throws IOException {
            int[] arr = {b};
            write(arr, 0, 1);
        }

        public void write(int[] bytes, int offset, int length) throws IOException {
            for (int i = 0; i < bytes.length; i++) {
                delegate.write(bytes[i]);

        new CacheLoader<String, String>() {
          @Override
          public String load(String key) throws InterruptedException {
            int behavior = random.nextInt(4);
            if (behavior == 0) { // throw an exception
              exceptionCount.incrementAndGet();
              throw new RuntimeException("fake exception for test");
            } else if (behavior == 1) { // return null

        new CacheLoader<String, String>() {
          @Override
          public String load(String key) throws InterruptedException {
            int behavior = random.nextInt(4);
            if (behavior == 0) { // throw an exception
              exceptionCount.incrementAndGet();
              throw new RuntimeException("fake exception for test");
            } else if (behavior == 1) { // return null

     */
    @Override
    protected int readBytesWireFormat(final byte[] buffer, final int bufferIndex) throws SMBProtocolDecodingException {
        final int start = bufferIndex;
        final int structureSize = SMBUtil.readInt2(buffer, bufferIndex);
        if (structureSize != 4) {
            throw new SMBProtocolDecodingException("Expected structureSize = 4");
        }
        return bufferIndex - start;
    }

        Objects.requireNonNull(output, "output cannot be null");
        Objects.requireNonNull(toolchains, "toolchains cannot be null");

        try (Writer out = output) {
            new MavenToolchainsStaxWriter().write(out, toolchains.getDelegate());
        } catch (XMLStreamException e) {
            throw new IOException("Error writing toolchains", e);
        }

  }

  @Override
  protected Map<K, V> delegate() {
    return delegate;
  }

  /** Returns its input, or throws an exception if this is not a valid key. */
  @CanIgnoreReturnValue
  @ParametricNullness
  K checkKey(@ParametricNullness K key) {
    return key;
  }

  /** Returns its input, or throws an exception if this is not a valid value. */
  @CanIgnoreReturnValue
  @ParametricNullness

   *
   * <p><b>Warning:</b> the results of calling this method may vary depending on the iteration order
   * of {@code map}.
   *
   * @throws IllegalArgumentException if an attempt to {@code put} any entry fails. Note that some
   *     map entries may have been added to the bimap before the exception was thrown.
   */
  @Override
  void putAll(Map<? extends K, ? extends V> map);

  // Views

  /**
   * {@inheritDoc}
   *

        return 0;
    }

    @Override
    protected int readDataWireFormat(final byte[] buffer, final int bufferIndex, final int len) throws SMBProtocolDecodingException {
        if (len > this.outputBuffer.length) {
            throw new SMBProtocolDecodingException("Payload exceeds buffer size");
        }
        System.arraycopy(buffer, bufferIndex, this.outputBuffer, 0, len);
        return len;
    }