public void AppendAllText_FileExist_ReturnAppendedFile() { _path = "player.json"; string firstcontent = "player****"; _target.WriteFileData(_path, firstcontent); string content = "volley"; _target.AppendAllText(_path, content); _expectedString = "player****volley"; var actual = _target.ReadFileData(_path); Assert.AreEqual(_expectedString, actual); }