scrapy/tests/test_request_cb_kwargs.py

from testfixtures import LogCapture
from twisted.internet import defer
from twisted.trial.unittest import TestCase

from scrapy.http import Request
from scrapy.utils.test import get_crawler
from tests.spiders import MockServerSpider
from tests.mockserver import MockServer


class InjectArgumentsDownloaderMiddleware:
    """
    Make sure downloader middlewares are able to update the keyword arguments
    """
    def process_request(self, request, spider):
        if request.callback.__name__ == 'parse_downloader_mw':
            request.cb_kwargs['from_process_request'] = True
        return None

    def process_response(self, request, response, spider):
        if request.callback.__name__ == 'parse_downloader_mw':
            request.cb_kwargs['from_process_response'] = True
        return response


class InjectArgumentsSpiderMiddleware:
    """
    Make sure spider middlewares are able to update the keyword arguments
    """
    def process_start_requests(self, start_requests, spider):
        for request in start_requests:
            if request.callback.__name__ == 'parse_spider_mw':
                request.cb_kwargs['from_process_start_requests'] = True
            yield request

    def process_spider_input(self, response, spider):
        request = response.request
        if request.callback.__name__ == 'parse_spider_mw':
            request.cb_kwargs['from_process_spider_input'] = True
        return None

    def process_spider_output(self, response, result, spider):
        for element in result:
            if isinstance(element, Request) and element.callback.__name__ == 'parse_spider_mw_2':
                element.cb_kwargs['from_process_spider_output'] = True
            yield element


class KeywordArgumentsSpider(MockServerSpider):
    name = 'kwargs'
    custom_settings = {
        'DOWNLOADER_MIDDLEWARES': {
            InjectArgumentsDownloaderMiddleware: 750,
        },
        'SPIDER_MIDDLEWARES': {
            InjectArgumentsSpiderMiddleware: 750,
        },
    }

    checks = []

    def start_requests(self):
        data = {'key': 'value', 'number': 123, 'callback': 'some_callback'}
        yield Request(self.mockserver.url('/first'), self.parse_first, cb_kwargs=data)
        yield Request(self.mockserver.url('/general_with'), self.parse_general, cb_kwargs=data)
        yield Request(self.mockserver.url('/general_without'), self.parse_general)
        yield Request(self.mockserver.url('/no_kwargs'), self.parse_no_kwargs)
        yield Request(self.mockserver.url('/default'), self.parse_default, cb_kwargs=data)
        yield Request(self.mockserver.url('/takes_less'), self.parse_takes_less, cb_kwargs=data)
        yield Request(self.mockserver.url('/takes_more'), self.parse_takes_more, cb_kwargs=data)
        yield Request(self.mockserver.url('/downloader_mw'), self.parse_downloader_mw)
        yield Request(self.mockserver.url('/spider_mw'), self.parse_spider_mw)

    def parse_first(self, response, key, number):
        self.checks.append(key == 'value')
        self.checks.append(number == 123)
        self.crawler.stats.inc_value('boolean_checks', 2)
        yield response.follow(
            self.mockserver.url('/two'),
            self.parse_second,
            cb_kwargs={'new_key': 'new_value'})

    def parse_second(self, response, new_key):
        self.checks.append(new_key == 'new_value')
        self.crawler.stats.inc_value('boolean_checks')

    def parse_general(self, response, **kwargs):
        if response.url.endswith('/general_with'):
            self.checks.append(kwargs['key'] == 'value')
            self.checks.append(kwargs['number'] == 123)
            self.checks.append(kwargs['callback'] == 'some_callback')
            self.crawler.stats.inc_value('boolean_checks', 3)
        elif response.url.endswith('/general_without'):
            self.checks.append(kwargs == {})  # pylint: disable=use-implicit-booleaness-not-comparison
            self.crawler.stats.inc_value('boolean_checks')

    def parse_no_kwargs(self, response):
        self.checks.append(response.url.endswith('/no_kwargs'))
        self.crawler.stats.inc_value('boolean_checks')

    def parse_default(self, response, key, number=None, default=99):
        self.checks.append(response.url.endswith('/default'))
        self.checks.append(key == 'value')
        self.checks.append(number == 123)
        self.checks.append(default == 99)
        self.crawler.stats.inc_value('boolean_checks', 4)

    def parse_takes_less(self, response, key, callback):
        """
        Should raise
        TypeError: parse_takes_less() got an unexpected keyword argument 'number'
        """

    def parse_takes_more(self, response, key, number, callback, other):
        """
        Should raise
        TypeError: parse_takes_more() missing 1 required positional argument: 'other'
        """

    def parse_downloader_mw(self, response, from_process_request, from_process_response):
        self.checks.append(bool(from_process_request))
        self.checks.append(bool(from_process_response))
        self.crawler.stats.inc_value('boolean_checks', 2)

    def parse_spider_mw(self, response, from_process_spider_input, from_process_start_requests):
        self.checks.append(bool(from_process_spider_input))
        self.checks.append(bool(from_process_start_requests))
        self.crawler.stats.inc_value('boolean_checks', 2)
        return Request(self.mockserver.url('/spider_mw_2'), self.parse_spider_mw_2)

    def parse_spider_mw_2(self, response, from_process_spider_output):
        self.checks.append(bool(from_process_spider_output))
        self.crawler.stats.inc_value('boolean_checks', 1)


class CallbackKeywordArgumentsTestCase(TestCase):

    maxDiff = None

    def setUp(self):
        self.mockserver = MockServer()
        self.mockserver.__enter__()

    def tearDown(self):
        self.mockserver.__exit__(None, None, None)

    @defer.inlineCallbacks
    def test_callback_kwargs(self):
        crawler = get_crawler(KeywordArgumentsSpider)
        with LogCapture() as log:
            yield crawler.crawl(mockserver=self.mockserver)
        self.assertTrue(all(crawler.spider.checks))
        self.assertEqual(len(crawler.spider.checks), crawler.stats.get_value('boolean_checks'))
        # check exceptions for argument mismatch
        exceptions = {}
        for line in log.records:
            for key in ('takes_less', 'takes_more'):
                if key in line.getMessage():
                    exceptions[key] = line
        self.assertEqual(exceptions['takes_less'].exc_info[0], TypeError)
        self.assertTrue(
            str(exceptions['takes_less'].exc_info[1]).endswith(
                "parse_takes_less() got an unexpected keyword argument 'number'"
            ),
            msg="Exception message: " + str(exceptions['takes_less'].exc_info[1]),
        )
        self.assertEqual(exceptions['takes_more'].exc_info[0], TypeError)
        self.assertTrue(
            str(exceptions['takes_more'].exc_info[1]).endswith(
                "parse_takes_more() missing 1 required positional argument: 'other'"
            ),
            msg="Exception message: " + str(exceptions['takes_more'].exc_info[1]),
        )