import org.jspecify.annotations.NullUnmarked;

/**
 * @author ricebin
 */
@NullUnmarked
public class MultiReaderTest extends TestCase {

  public void testOnlyOneOpen() throws Exception {
    String testString = "abcdefgh";
    CharSource source = newCharSource(testString);
    int[] counter = new int[1];
    CharSource reader =
        new CharSource() {
          @Override
          public Reader openStream() throws IOException {

 *
 * {@snippet :
 *        h
 *      / | \
 *     /  e  \
 *    d       g
 *   /|\      |
 *  / | \     f
 * a  b  c
 * }
 *
 * <p>can be iterated over in preorder (hdabcegf), postorder (abcdefgh), or breadth-first order
 * (hdegabcf).
 *
 * <p>Null nodes are strictly forbidden.
 *
 * <p>Because this is an abstract class, not an interface, you can't use a lambda expression to
 * implement it:
 *

 *
 * {@snippet :
 *        h
 *      / | \
 *     /  e  \
 *    d       g
 *   /|\      |
 *  / | \     f
 * a  b  c
 * }
 *
 * <p>can be iterated over in preorder (hdabcegf), postorder (abcdefgh), or breadth-first order
 * (hdegabcf).
 *
 * <p>Null nodes are strictly forbidden.
 *
 * <p>Because this is an abstract class, not an interface, you can't use a lambda expression to
 * implement it:
 *