assertThat(e).hasMessageThat().contains(ERROR_SELF_LOOP);
  }

  /**
   * This test checks an implementation dependent feature. It tests that the method {@code addEdge}
   * will silently add the missing nodes to the graph, then add the edge connecting them. We are not
   * using the proxy methods here as we want to test {@code addEdge} when the end-points are not
   * elements of the graph.
   */
  @Test

            IllegalArgumentException.class, () -> graph.removeEdge(EndpointPair.ordered(2, 1)));
    assertThat(e).hasMessageThat().contains(ENDPOINTS_MISMATCH);
  }

  @Test
  public void edgeValue_missing() {
    graph = ValueGraphBuilder.directed().build();

    assertThat(graph.edgeValueOrDefault(1, 2, DEFAULT)).isEqualTo(DEFAULT);
    assertThat(graph.edgeValueOrDefault(2, 1, DEFAULT)).isEqualTo(DEFAULT);

    assertThat(e).hasMessageThat().contains(ERROR_SELF_LOOP);
  }

  /**
   * This test checks an implementation dependent feature. It tests that the method {@code addEdge}
   * will silently add the missing nodes to the graph, then add the edge connecting them. We are not
   * using the proxy methods here as we want to test {@code addEdge} when the end-points are not
   * elements of the graph.
   */
  @Test

import java.util.Set;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

/**
 * Tests for {@link Graphs}. Tests assume that the implementation of the method {@code addEdge} adds
 * the missing nodes to the graph, then adds the edge between them.
 */
@RunWith(JUnit4.class)
public class GraphsTest {
  private static final Integer N1 = 1;
  private static final Integer N2 = 2;

    assertEquals(multimap.hashCode(), unmodifiable.hashCode());
    assertEquals(multimap, unmodifiable);

    assertThat(unmodifiable.asMap().get("bar")).containsExactly(5, -1);
    assertNull(unmodifiable.asMap().get("missing"));

    assertFalse(unmodifiable.entries() instanceof Serializable);
  }

  /** Prepares the multimap for unmodifiable tests, returning an unmodifiable view of the map. */

  public void testGoodClass() {
    shouldPass(new PassObject());
  }

  private static class FailOneArgDoesntThrowNPE extends PassObject {
    @Override
    public void oneArg(String s) {
      // Fail:  missing NPE for s
    }
  }

  public void testFailOneArgDoesntThrowNpe() {
    shouldFail(new FailOneArgDoesntThrowNPE());
  }

  private static class FailOneArgThrowsWrongType extends PassObject {

    TreeMultimap<@Nullable String, @Nullable Integer> multimap = createPopulate();
    assertEquals(DECREASING_INT_COMPARATOR, multimap.get("foo").comparator());
    assertEquals(DECREASING_INT_COMPARATOR, multimap.get("missing").comparator());
  }

  public void testMultimapComparators() {
    Multimap<String, Integer> multimap = create();
    multimap.put("foo", 3);
    multimap.put("bar", 1);

        return compareResult == 0;
      } catch (ClassCastException wastNotComparableToOurType) {
        return false;
      }
    }
    return false;
  }

  // Prevent "missing hashCode" warning by explicitly forcing subclasses implement it
  @Override
  public abstract int hashCode();

  /*
   * The implementation neither produces nor consumes any non-null instance of type C, so

        //
        // Note that there is a race condition here which can result in missing
        // a cyclic edge: it's possible for two threads to simultaneous find
        // "safe" edges which together form a cycle. Preventing this race
        // condition efficiently without _introducing_ deadlock is probably
        // tricky. For now, just accept the race condition---missing a warning

            IllegalArgumentException.class, () -> graph.removeEdge(EndpointPair.ordered(2, 1)));
    assertThat(e).hasMessageThat().contains(ENDPOINTS_MISMATCH);
  }

  @Test
  public void edgeValue_missing() {
    graph = ValueGraphBuilder.directed().build();

    assertThat(graph.edgeValueOrDefault(1, 2, DEFAULT)).isEqualTo(DEFAULT);
    assertThat(graph.edgeValueOrDefault(2, 1, DEFAULT)).isEqualTo(DEFAULT);