*
 * <p>Provides an {@link java.util.concurrent.Executor} implementation, which uses test threads to execute any tasks
 * submitted to it.</p>
 *
 * <p>You can use {@link #syncAt(int)} and {@link #expectBlocksUntil(int, groovy.lang.Closure)} to synchronise between
 * test threads.</p>
 */
public class MultithreadedTestRule extends ExternalResource {