def METHOD_NAME(self):
    """If a single year is given, range starts from this year and stops at
    the year preceding the one of next bucket."""
    self._setup_config(bucket_year=['1950s', '1970s'])
    self.assertEqual(self.plugin._tmpl_bucket('1959'), '1950s')
    self.assertEqual(self.plugin._tmpl_bucket('1969'), '1950s')