async def METHOD_NAME(self):
    response_mock = ResponseMock(body="", code=200)
    ctx = Context(None, None, None)
    result = loader.return_contents(response_mock, "some-url", ctx)
    expect(result).to_be_instance_of(LoaderResult)
    expect(result.buffer).to_be_null()
    expect(result.successful).to_be_false()
    expect(result.error).to_equal(LoaderResult.ERROR_UPSTREAM)