Map<Path, Set<Integer>> changedLines() {
    return tracker.changedLines();
  }
@Test
  public void count_single_added_line() throws IOException {
    String example = "Index: sample1\n"
      + "===================================================================\n"
      + "--- a/sample1\n"
      + "+++ b/sample1\n"
      + "@@ -0,0 +1 @@\n"
      + "+added line\n";

    printDiff(example);
    assertThat(underTest.changedLines()).isEqualTo(Collections.singletonMap(rootBaseDir.resolve("sample1"), singleton(1)));
  }