private final EdgeType edgeType;
  private final MutableNetwork<Integer, String> network;

  // add parameters: directed/undirected
  @Parameters
  public static Collection<Object[]> parameters() {
    return Arrays.asList(new Object[][] {{EdgeType.UNDIRECTED}, {EdgeType.DIRECTED}});
  }

  public NetworkEquivalenceTest(EdgeType edgeType) {
    this.edgeType = edgeType;
    this.network = createNetwork(edgeType);

  private final EdgeType edgeType;
  private final MutableNetwork<Integer, String> network;

  // add parameters: directed/undirected
  @Parameters
  public static Collection<Object[]> parameters() {
    return Arrays.asList(new Object[][] {{EdgeType.UNDIRECTED}, {EdgeType.DIRECTED}});
  }

  public NetworkEquivalenceTest(EdgeType edgeType) {
    this.edgeType = edgeType;
    this.network = createNetwork(edgeType);

   * that edge to {@code value} (overwriting the existing value, if any).
   *
   * <p>If the graph is directed, the resultant edge will be directed; otherwise, it will be
   * undirected.
   *
   * <p>If this graph is directed, {@code endpoints} must be ordered.
   *
   * <p>Values do not have to be unique. However, values must be non-null.
   *

      requireNonNull(nodeConnections.getWithoutCaching(successor)).removePredecessor(node);
      requireNonNull(connections.removeSuccessor(successor));
      --edgeCount;
    }
    if (isDirected()) { // In undirected graphs, the successor and predecessor sets are equal.
      // Since views are returned, we need to copy the predecessors that will be removed.
      // Thus we avoid modifying the underlying view while iterating over it.

  Network<Integer, String> undirectedNetwork;

  @Before
  public void init() {
    MutableGraph<Integer> mutableDirectedGraph =
        GraphBuilder.directed().allowsSelfLoops(true).build();
    MutableGraph<Integer> mutableUndirectedGraph =
        GraphBuilder.undirected().allowsSelfLoops(true).build();
    graphsToTest = ImmutableList.of(mutableDirectedGraph, mutableUndirectedGraph);
    directedGraph = mutableDirectedGraph;

  /**
   * Adds {@code edge} connecting {@code endpoints}. In an undirected network, {@code edge} will
   * also connect {@code nodeV} to {@code nodeU}.
   *
   * <p>If this graph is directed, {@code edge} will be directed in this graph; if it is undirected,
   * {@code edge} will be undirected in this graph.
   *
   * <p>If this graph is directed, {@code endpoints} must be ordered.
   *

  //
  // Graph properties
  //

  /**
   * Returns true if the edges in this graph are directed. Directed edges connect a {@link
   * EndpointPair#source() source node} to a {@link EndpointPair#target() target node}, while
   * undirected edges connect a pair of nodes to each other.
   */
  @Override
  boolean isDirected();

  /**

import java.util.Collection;
import org.jspecify.annotations.NullUnmarked;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;
import org.junit.runners.Parameterized.Parameters;

/** Tests for an undirected {@link StandardMutableGraph}. */
@AndroidIncompatible
@RunWith(Parameterized.class)
@NullUnmarked
public class StandardMutableUndirectedGraphTest extends AbstractStandardUndirectedGraphTest {

 *
 * <p>{@code Network} supports the following use cases (<a
 * href="https://github.com/google/guava/wiki/GraphsExplained#definitions">definitions of
 * terms</a>):
 *
 * <ul>
 *   <li>directed graphs
 *   <li>undirected graphs
 *   <li>graphs that do/don't allow parallel edges
 *   <li>graphs that do/don't allow self-loops
 *   <li>graphs whose nodes/edges are insertion-ordered, sorted, or unordered

  private GraphBuilder(boolean directed) {
    super(directed);
  }

  /** Returns a {@link GraphBuilder} for building directed graphs. */
  public static GraphBuilder<Object> directed() {
    return new GraphBuilder<>(true);
  }

  /** Returns a {@link GraphBuilder} for building undirected graphs. */
  public static GraphBuilder<Object> undirected() {
    return new GraphBuilder<>(false);
  }

  /**