def METHOD_NAME(self):
    expected = {
        "sources": "Help on package snapcraft",
        "plugins": "Help on package snapcraft",
    }
    for topic in _TOPICS:
        result = self.run_command(["help", topic, "--devel"])
        output = result.output[: len(expected[topic])]
        self.assertThat(
            output,
            Equals(expected[topic]),
            "The help message does not start with {!r} but with "
            "{!r} instead".format(expected[topic], output),
        )