@NullUnmarked
public class FilesFileTraverserTest extends IoTestCase {

  private File rootDir;

  @Override
  public void setUp() throws IOException {
    rootDir = createTempDir();
  }

  public void testFileTraverser_emptyDirectory() throws Exception {
    assertThat(Files.fileTraverser().breadthFirst(rootDir)).containsExactly(rootDir);
  }

  public void testFileTraverser_nonExistingFile() throws Exception {