async def METHOD_NAME(  # NOQA
    self, request_mock
):
    def side_effect(*_, **kwargs):
        req = RequestParameters(**kwargs)
        req.auto_png_to_jpg = False
        return req
    request_mock.side_effect = side_effect
    response = await self.async_fetch(
        "/unsafe/Giunchedi%2C_Filippo_January_2015_01.png"
    )
    expect(response.code).to_equal(200)
    expect(response.headers).not_to_include("Vary")
    expect(response.body).to_be_png()