assertThat(graphAsMutableGraph.putEdge(N2, N3)).isTrue();
    assertThat(graph.nodes()).containsExactly(N1, N5, N4, N2, N3).inOrder();
    assertThat(graph.successors(N1)).containsExactly(N5);
    assertThat(graph.successors(N2)).containsExactly(N3);
    assertThat(graph.successors(N3)).isEmpty();
    assertThat(graph.successors(N4)).containsExactly(N1);
    assertThat(graph.successors(N5)).isEmpty();
  }

  @Test

   *
   * <p>If the graph is directed, the resultant edge will be directed; otherwise, it will be
   * undirected.
   *
   * <p>If {@code nodeU} and {@code nodeV} are not already present in this graph, this method will
   * silently {@link #addNode(Object) add} {@code nodeU} and {@code nodeV} to the graph.
   *
   * @return {@code true} if the graph was modified as a result of this call

        + edgeValueMap(this);
  }

  private static <N, V> Map<EndpointPair<N>, V> edgeValueMap(ValueGraph<N, V> graph) {
    return Maps.asMap(
        graph.edges(),
        edge ->
            // requireNonNull is safe because the endpoint pair comes from the graph.
            requireNonNull(graph.edgeValueOrDefault(edge.nodeU(), edge.nodeV(), null)));
  }

 *
 * @author higa
 */
public abstract class PropertiesUtil {

    /**
     * Do not instantiate.
     */
    protected PropertiesUtil() {
    }

    /**
     * Wraps exception handling for {@link Properties#load(InputStream)}.
     * <p>
     * The input stream is not closed.
     * </p>
     *
     * @param props the property set (must not be {@literal null})

  static final String EDGE_NOT_IN_GRAPH = "Edge %s is not an element of this graph.";
  static final String NODE_REMOVED_FROM_GRAPH =
      "Node %s that was used to generate this set is no longer in the graph.";
  static final String NODE_PAIR_REMOVED_FROM_GRAPH =
      "Node %s or node %s that were used to generate this set are no longer in the graph.";
  static final String EDGE_REMOVED_FROM_GRAPH =

    protected String line = EMPTY;

    /**
     * Returns an {@link Iterable} that wraps a {@link LineIterator} for use in enhanced for-loops.
     *
     * @param reader
     *            The {@link Reader} to read strings from. Must not be {@literal null}.
     * @return An {@link Iterable} that wraps a {@link LineIterator}.
     */
    public static Iterable<String> iterable(final Reader reader) {

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.graph;

import static com.google.common.graph.TestUtil.ERROR_ELEMENT_NOT_IN_GRAPH;
import static com.google.common.truth.Truth.assertWithMessage;

import com.google.common.testing.AbstractPackageSanityTests;

 * limitations under the License.
 */

package com.google.common.graph;

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.Iterator;
import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * An interface for representing and manipulating an origin node's adjacent nodes and edge values in
 * a {@link Graph}.
 *
 * @author James Sexton
 * @param <N> Node parameter type

    // ordered endpoints not compatible with undirected graph
    assertThat(edges).doesNotContain(EndpointPair.ordered(N1, N2));

    assertThat(edges).doesNotContain(EndpointPair.unordered(N2, N2)); // edge not present
    assertThat(edges).doesNotContain(EndpointPair.unordered(N3, N4)); // nodes not in graph
  }

  @Test
  public void endpointPair_directed_contains() {

    // ordered endpoints not compatible with undirected graph
    assertThat(edges).doesNotContain(EndpointPair.ordered(N1, N2));

    assertThat(edges).doesNotContain(EndpointPair.unordered(N2, N2)); // edge not present
    assertThat(edges).doesNotContain(EndpointPair.unordered(N3, N4)); // nodes not in graph
  }

  @Test
  public void endpointPair_directed_contains() {