}

  @Test
  public void degree_oneEdge() {
    putEdge(N1, N2);
    assertThat(graph.degree(N1)).isEqualTo(1);
    assertThat(graph.degree(N2)).isEqualTo(1);
  }

  @Test
  public void degree_isolatedNode() {
    addNode(N1);
    assertThat(graph.degree(N1)).isEqualTo(0);
  }

  @Test
  public void degree_nodeNotInGraph() {
    assertNodeNotInGraphErrorMessage(

  }

  @Test
  public void degree_oneEdge() {
    putEdge(N1, N2);
    assertThat(graph.degree(N1)).isEqualTo(1);
    assertThat(graph.degree(N2)).isEqualTo(1);
  }

  @Test
  public void degree_isolatedNode() {
    addNode(N1);
    assertThat(graph.degree(N1)).isEqualTo(0);
  }

  @Test
  public void degree_nodeNotInGraph() {
    assertNodeNotInGraphErrorMessage(

   */
  protected long edgeCount() {
    long degreeSum = 0L;
    for (N node : nodes()) {
      degreeSum += degree(node);
    }
    // According to the degree sum formula, this is equal to twice the number of edges.
    checkState((degreeSum & 1) == 0);
    return degreeSum >>> 1;
  }

  /**

        .containsExactly(EndpointPair.ordered(N1, N1), EndpointPair.ordered(N1, N2));
  }

  @Test
  public void degree_selfLoop() {
    assume().that(graph.allowsSelfLoops()).isTrue();

    putEdge(N1, N1);
    assertThat(graph.degree(N1)).isEqualTo(2);
    putEdge(N1, N2);
    assertThat(graph.degree(N1)).isEqualTo(3);
  }

  @Test
  public void inDegree_selfLoop() {

  private GraphConstants() {}

  static final int EXPECTED_DEGREE = 2;

  static final int DEFAULT_NODE_COUNT = 10;
  static final int DEFAULT_EDGE_COUNT = DEFAULT_NODE_COUNT * EXPECTED_DEGREE;

  // Load factor and capacity for "inner" (i.e. per node/edge element) hash sets or maps
  static final float INNER_LOAD_FACTOR = 1.0f;
  static final int INNER_CAPACITY = 2; // ceiling(EXPECTED_DEGREE / INNER_LOAD_FACTOR)

  // Error messages

      @Override
      public Set<N> successors(N node) {
        return AbstractNetwork.this.successors(node);
      }

      // DO NOT override the AbstractGraph *degree() implementations.
    };
  }

  @Override
  public int degree(N node) {
    if (isDirected()) {
      return IntMath.saturatedAdd(inEdges(node).size(), outEdges(node).size());
    } else {

   *
   * @throws IllegalArgumentException if {@code node} is not an element of this graph
   */
  @Override
  int degree(N node);

  /**
   * Returns the count of {@code node}'s incoming edges (equal to {@code predecessors(node).size()})
   * in a directed graph. In an undirected graph, returns the {@link #degree(Object)}.
   *
   * <p>If the count is greater than {@code Integer.MAX_VALUE}, returns {@code Integer.MAX_VALUE}.
   *

        .containsExactly(EndpointPair.unordered(N1, N1), EndpointPair.unordered(N1, N2));
  }

  @Test
  public void degree_selfLoop() {
    assume().that(graph.allowsSelfLoops()).isTrue();

    putEdge(N1, N1);
    assertThat(graph.degree(N1)).isEqualTo(2);
    putEdge(N1, N2);
    assertThat(graph.degree(N1)).isEqualTo(3);
  }

  @Test
  public void inDegree_selfLoop() {

      }

      @Override
      public Set<N> successors(N node) {
        return AbstractValueGraph.this.successors(node);
      }

      @Override
      public int degree(N node) {
        return AbstractValueGraph.this.degree(node);
      }

      @Override
      public int inDegree(N node) {
        return AbstractValueGraph.this.inDegree(node);
      }

      @Override

    assertThat(network.incidentNodes(E11).target()).isEqualTo(N1);
  }

  @Test
  public void degree_selfLoop() {
    assume().that(network.allowsSelfLoops()).isTrue();

    addEdge(N1, N1, E11);
    assertThat(network.degree(N1)).isEqualTo(2);
    addEdge(N1, N2, E12);
    assertThat(network.degree(N1)).isEqualTo(3);
  }

  @Test
  public void inDegree_selfLoop() {