anchor.diff:    text2 = '${text1}123';
     expectedPatch = '@@ -573,28 +573,31 @@\n cdefabcdefabcdefabcdefabcdef\n+123\n';
     patches = dmp.patch_make(text1, text2);
  -  Expect.equals(expectedPatch, dmp.patch_toText(patches), 'patch_make: Long string with repeats.');
  +  expect(expectedPatch, dmp.patch_toText(patches), reason: 'patch_make: Long string with repeats.');
   
     // Test null inputs.
     Expect.throws(() => dmp.patch_make(null), null, 'patch_make: Null inputs.');
  
positive.code:     lineList.add('$x\n');
      charList.write(new String.fromCharCodes([x]));
    }
    Expect.equals(n, lineList.length);
    String lines = lineList.join();
    String chars = charList.toString();
    Expect.equals(n, chars.length);
    lineList.insertRange(0, 1, '');
    assertLinesToCharsResultEquals({'chars1': chars, 'chars2': '', 'lineArray': lineList}, dmp._diff_linesToChars(lines, ''), 'diff_linesToChars: More than 256.');
  }
  
negative.code: void testDiffXIndex() {
    // Translate a location in text1 to text2.
    List<Diff> diffs = [new Diff(DIFF_DELETE, 'a'), new Diff(DIFF_INSERT, '1234'), new Diff(DIFF_EQUAL, 'xyz')];
    expect(5, dmp.diff_xIndex(diffs, 2), reason: 'diff_xIndex: Translation on equality.');
  
    diffs = [new Diff(DIFF_EQUAL, 'a'), new Diff(DIFF_DELETE, '1234'), new Diff(DIFF_EQUAL, 'xyz')];
    expect(1, dmp.diff_xIndex(diffs, 3), reason: 'diff_xIndex: Translation on deletion.');
  }
  
  void testDiffLevenshtein() {
    List<Diff> diffs = [new Diff(DIFF_DELETE, 'abc'), new Diff(DIFF_INSERT, '1234'), new Diff(DIFF_EQUAL, 'xyz')];
    expect(4, dmp.diff_levenshtein(diffs), reason: 'Levenshtein with trailing equality.');
  
    diffs = [new Diff(DIFF_EQUAL, 'xyz'), new Diff(DIFF_DELETE, 'abc'), new Diff(DIFF_INSERT, '1234')];
    expect(4, dmp.diff_levenshtein(diffs), reason: 'Levenshtein with leading equality.');
  
    diffs = [new Diff(DIFF_DELETE, 'abc'), new Diff(DIFF_EQUAL, 'xyz'), new Diff(DIFF_INSERT, '1234')];
    expect(7, dmp.diff_levenshtein(diffs), reason: 'Levenshtein with middle equality.');
  }
  
  void testDiffBisect() {
  