assertEquals(20, counter.read(new byte[30]));
    assertEquals(20, counter.getCount());
    assertEquals(-1, counter.read(new byte[30]));
    assertEquals(20, counter.getCount());
  }

  @SuppressWarnings("CheckReturnValue") // calling read() to skip a byte
  public void testMark() throws Exception {
    assertTrue(counter.markSupported());
    assertEquals(10, counter.read(new byte[10]));
    assertEquals(10, counter.getCount());

  }

  /**
   * Tests that the ImmutableGraph.Builder doesn't change when the creating GraphBuilder changes.
   */
  @Test
  @SuppressWarnings("CheckReturnValue")
  public void immutableGraphBuilder_copiesGraphBuilder() {
    GraphBuilder<String> graphBuilder =
        GraphBuilder.directed()
            .allowsSelfLoops(true)

  }

  /**
   * Tests that the ImmutableNetwork.Builder doesn't change when the creating NetworkBuilder
   * changes.
   */
  @Test
  @SuppressWarnings("CheckReturnValue")
  public void immutableNetworkBuilder_copiesNetworkBuilder() {
    NetworkBuilder<String, Object> networkBuilder =
        NetworkBuilder.directed()
            .allowsSelfLoops(true)

  }

  /**
   * Tests that the ImmutableNetwork.Builder doesn't change when the creating NetworkBuilder
   * changes.
   */
  @Test
  @SuppressWarnings("CheckReturnValue")
  public void immutableNetworkBuilder_copiesNetworkBuilder() {
    NetworkBuilder<String, Object> networkBuilder =
        NetworkBuilder.directed()
            .allowsSelfLoops(true)

      assertTrue(Thread.holdsLock(mutex));
      return delegate.descendingIterator();
    }

    private static final long serialVersionUID = 0;
  }

  @SuppressWarnings("CheckReturnValue")
  public void testHoldsLockOnAllOperations() {
    create().element();
    create().offer("foo");
    create().peek();
    create().poll();
    create().remove();
    create().add("foo");

      assertTrue(Thread.holdsLock(mutex));
      return delegate.toArray(array);
    }

    private static final long serialVersionUID = 0;
  }

  @SuppressWarnings("CheckReturnValue")
  public void testHoldsLockOnAllOperations() {
    create().element();
    create().offer("foo");
    create().peek();
    create().poll();
    create().remove();
    create().add("foo");

  }

  /**
   * Tests that the ImmutableValueGraph.Builder doesn't change when the creating ValueGraphBuilder
   * changes.
   */
  @Test
  @SuppressWarnings("CheckReturnValue")
  public void immutableValueGraphBuilder_copiesGraphBuilder() {
    ValueGraphBuilder<String, Object> graphBuilder =
        ValueGraphBuilder.directed()
            .allowsSelfLoops(true)

      assertTrue(Thread.holdsLock(mutex));
      return delegate.descendingIterator();
    }

    private static final long serialVersionUID = 0;
  }

  @SuppressWarnings("CheckReturnValue")
  public void testHoldsLockOnAllOperations() {
    create().element();
    create().offer("foo");
    create().peek();
    create().poll();
    create().remove();
    create().add("foo");

    assertEqualCharNodes(Iterables.limit(result, 2), "db");
    assertThat(graph.requestedNodes).containsExactly('a', 'a', 'a', 'b', 'b', 'c', 'd', 'd');
  }

  @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

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import com.google.errorprone.annotations.CheckReturnValue;
import com.google.errorprone.annotations.ForOverride;
import com.google.errorprone.annotations.InlineMe;
import com.google.errorprone.annotations.concurrent.LazyInit;
import com.google.j2objc.annotations.RetainedWith;