import org.jspecify.annotations.NullUnmarked;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

@RunWith(JUnit4.class)
@NullUnmarked
public class TraverserTest {

  /**
   * The undirected graph in the {@link Traverser#breadthFirst(Object)} javadoc:
   *
   * {@snippet :
   * b ---- a ---- d
   * |      |
   * |      |
   * e ---- c ---- f
   * }
   */