testComparator(arbitrary, list);
  }

  public void testUsingToString() {
    Ordering<Object> ordering = Ordering.usingToString();
    testComparator(ordering, 1, 12, 124, 2);
    assertEquals("Ordering.usingToString()", ordering.toString());
    assertSame(ordering, reserialize(ordering));
  }

  // use an enum to get easy serializability

    testComparator(arbitrary, list);
  }

  public void testUsingToString() {
    Ordering<Object> ordering = Ordering.usingToString();
    testComparator(ordering, 1, 12, 124, 2);
    assertEquals("Ordering.usingToString()", ordering.toString());
    assertSame(ordering, reserialize(ordering));
  }

  // use an enum to get easy serializability

   */
  @WeakOuter
  class Heap {
    final Ordering<E> ordering;

    @SuppressWarnings("nullness:initialization.field.uninitialized")
    @Weak
    Heap otherHeap; // always initialized immediately after construction

    Heap(Ordering<E> ordering) {
      this.ordering = ordering;
    }

    int compareElements(int a, int b) {
      return ordering.compare(elementData(a), elementData(b));
    }

      GeneralRange<@Nullable Integer> range = GeneralRange.downTo(ORDERING, 3, lBoundType);
      for (Integer i : IN_ORDER_VALUES) {
        assertEquals(
            ORDERING.compare(i, 3) > 0 || (ORDERING.compare(i, 3) == 0 && lBoundType == CLOSED),
            range.contains(i));
        assertEquals(
            ORDERING.compare(i, 3) < 0 || (ORDERING.compare(i, 3) == 0 && lBoundType == OPEN),
            range.tooLow(i));

    assertEquals(tree, copyFromTree);
    assertSame(Ordering.natural(), copyFromTree.keyComparator());
    assertSame(Ordering.natural(), copyFromTree.valueComparator());
    assertSame(Ordering.natural(), copyFromTree.get(1.0).comparator());
  }

  /** Test that creating one TreeMultimap from a non-TreeMultimap results in natural ordering. */
  public void testCreateFromHashMultimap() {

    lockA.lock();
  }

  // Tests transitive deadlock detection.
  public void testDeadlock_threeLocks() {
    // Establish an ordering from lockA -> lockB.
    lockA.lock();
    lockB.lock();
    lockB.unlock();
    lockA.unlock();

    // Establish an ordering from lockB -> lockC.
    lockB.lock();
    lockC.lock();
    lockB.unlock();

    // lockC -> lockA should fail.

    lockA.lock();
  }

  // Tests transitive deadlock detection.
  public void testDeadlock_threeLocks() {
    // Establish an ordering from lockA -> lockB.
    lockA.lock();
    lockB.lock();
    lockB.unlock();
    lockA.unlock();

    // Establish an ordering from lockB -> lockC.
    lockB.lock();
    lockC.lock();
    lockB.unlock();

    // lockC -> lockA should fail.

/** An ordering that treats {@code null} as less than all other values. */
@GwtCompatible(serializable = true)
@ElementTypesAreNonnullByDefault
final class NullsFirstOrdering<T extends @Nullable Object> extends Ordering<@Nullable T>
    implements Serializable {
  final Ordering<? super T> ordering;

  NullsFirstOrdering(Ordering<? super T> ordering) {
    this.ordering = ordering;
  }

  @Override

import static com.google.common.graph.ElementOrder.unordered;
import static com.google.common.truth.Truth.assertThat;

import com.google.common.collect.Ordering;
import java.util.Comparator;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

/** Tests for ordering the elements of graphs. */
@RunWith(JUnit4.class)
public final class ElementOrderTest {
  // Node order tests

  @Test

  @Override
  public <S extends Comparable<?>> Ordering<@Nullable S> nullsFirst() {
    Ordering<@Nullable Comparable<?>> result = nullsFirst;
    if (result == null) {
      result = nullsFirst = super.<Comparable<?>>nullsFirst();
    }
    return (Ordering<@Nullable S>) result;
  }

  @Override
  public <S extends Comparable<?>> Ordering<@Nullable S> nullsLast() {
    Ordering<@Nullable Comparable<?>> result = nullsLast;