def METHOD_NAME(self):
    report = deprecated.Report("some-policy", actions=[
        deprecated.Context(
            'mark-for-op:', deprecated.optional_fields(('hours', 'days'), '2021-06-30')),
        deprecated.Context(
            'mark-for-op:', deprecated.optional_field('tag', '2021-06-30')),
    ])
    self.assertTrue(report)
    self.assertEqual(report.format(), dedent("""
        policy 'some-policy'
          actions:
            mark-for-op: optional fields deprecated (one of 'hours' or 'days' must be specified)
            mark-for-op: optional field 'tag' deprecated (must be specified)
        """)[1:-1])