'2to3 a single file with a new output dir.'

def test_filename_changing_on_output_single_file(self):

    self.setup_test_source_trees()
    err = io.StringIO()
    ret = self.run_2to3_capture(['-n', '-w', '--no-diffs', '--output-dir', self.py3_dest_dir, self.trivial_py2_file], io.StringIO(''), io.StringIO(), err)
    self.assertEqual(ret, 0)
    stderr = err.getvalue()
    self.assertIn(('Output    in    %r    will    mirror    the    input    directory    %r    layout' % (self.py3_dest_dir, self.py2_src_dir)), stderr)
    self.assertEqual(set([os.path.basename(self.trivial_py2_file)]), set(os.listdir(self.py3_dest_dir)))
