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test_downloadermiddleware_httpcache.py
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test_downloadermiddleware_httpcache.py
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import time
import tempfile
import shutil
import unittest
import email.utils
from contextlib import contextmanager
from scrapy.http import Response, HtmlResponse, Request
from scrapy.spiders import Spider
from scrapy.settings import Settings
from scrapy.exceptions import IgnoreRequest
from scrapy.utils.test import get_crawler
from scrapy.downloadermiddlewares.httpcache import HttpCacheMiddleware
class _BaseTest(unittest.TestCase):
storage_class = 'scrapy.extensions.httpcache.DbmCacheStorage'
policy_class = 'scrapy.extensions.httpcache.RFC2616Policy'
def setUp(self):
self.yesterday = email.utils.formatdate(time.time() - 86400)
self.today = email.utils.formatdate()
self.tomorrow = email.utils.formatdate(time.time() + 86400)
self.crawler = get_crawler(Spider)
self.spider = self.crawler._create_spider('example.com')
self.tmpdir = tempfile.mkdtemp()
self.request = Request('http://www.example.com',
headers={'User-Agent': 'test'})
self.response = Response('http://www.example.com',
headers={'Content-Type': 'text/html'},
body=b'test body',
status=202)
self.crawler.stats.open_spider(self.spider)
def tearDown(self):
self.crawler.stats.close_spider(self.spider, '')
shutil.rmtree(self.tmpdir)
def _get_settings(self, **new_settings):
settings = {
'HTTPCACHE_ENABLED': True,
'HTTPCACHE_DIR': self.tmpdir,
'HTTPCACHE_EXPIRATION_SECS': 1,
'HTTPCACHE_IGNORE_HTTP_CODES': [],
'HTTPCACHE_POLICY': self.policy_class,
'HTTPCACHE_STORAGE': self.storage_class,
}
settings.update(new_settings)
return Settings(settings)
@contextmanager
def _storage(self, **new_settings):
with self._middleware(**new_settings) as mw:
yield mw.storage
@contextmanager
def _policy(self, **new_settings):
with self._middleware(**new_settings) as mw:
yield mw.policy
@contextmanager
def _middleware(self, **new_settings):
settings = self._get_settings(**new_settings)
mw = HttpCacheMiddleware(settings, self.crawler.stats)
mw.spider_opened(self.spider)
try:
yield mw
finally:
mw.spider_closed(self.spider)
def assertEqualResponse(self, response1, response2):
self.assertEqual(response1.url, response2.url)
self.assertEqual(response1.status, response2.status)
self.assertEqual(response1.headers, response2.headers)
self.assertEqual(response1.body, response2.body)
def assertEqualRequest(self, request1, request2):
self.assertEqual(request1.url, request2.url)
self.assertEqual(request1.headers, request2.headers)
self.assertEqual(request1.body, request2.body)
def assertEqualRequestButWithCacheValidators(self, request1, request2):
self.assertEqual(request1.url, request2.url)
assert b'If-None-Match' not in request1.headers
assert b'If-Modified-Since' not in request1.headers
assert any(h in request2.headers for h in (b'If-None-Match', b'If-Modified-Since'))
self.assertEqual(request1.body, request2.body)
def test_dont_cache(self):
with self._middleware() as mw:
self.request.meta['dont_cache'] = True
mw.process_response(self.request, self.response, self.spider)
self.assertEqual(mw.storage.retrieve_response(self.spider, self.request), None)
with self._middleware() as mw:
self.request.meta['dont_cache'] = False
mw.process_response(self.request, self.response, self.spider)
if mw.policy.should_cache_response(self.response, self.request):
self.assertIsInstance(mw.storage.retrieve_response(self.spider, self.request), self.response.__class__)
class DefaultStorageTest(_BaseTest):
def test_storage(self):
with self._storage() as storage:
request2 = self.request.copy()
assert storage.retrieve_response(self.spider, request2) is None
storage.store_response(self.spider, self.request, self.response)
response2 = storage.retrieve_response(self.spider, request2)
assert isinstance(response2, HtmlResponse) # content-type header
self.assertEqualResponse(self.response, response2)
time.sleep(2) # wait for cache to expire
assert storage.retrieve_response(self.spider, request2) is None
def test_storage_never_expire(self):
with self._storage(HTTPCACHE_EXPIRATION_SECS=0) as storage:
assert storage.retrieve_response(self.spider, self.request) is None
storage.store_response(self.spider, self.request, self.response)
time.sleep(0.5) # give the chance to expire
assert storage.retrieve_response(self.spider, self.request)
class DbmStorageTest(DefaultStorageTest):
storage_class = 'scrapy.extensions.httpcache.DbmCacheStorage'
class DbmStorageWithCustomDbmModuleTest(DbmStorageTest):
dbm_module = 'tests.mocks.dummydbm'
def _get_settings(self, **new_settings):
new_settings.setdefault('HTTPCACHE_DBM_MODULE', self.dbm_module)
return super()._get_settings(**new_settings)
def test_custom_dbm_module_loaded(self):
# make sure our dbm module has been loaded
with self._storage() as storage:
self.assertEqual(storage.dbmodule.__name__, self.dbm_module)
class FilesystemStorageTest(DefaultStorageTest):
storage_class = 'scrapy.extensions.httpcache.FilesystemCacheStorage'
class FilesystemStorageGzipTest(FilesystemStorageTest):
def _get_settings(self, **new_settings):
new_settings.setdefault('HTTPCACHE_GZIP', True)
return super()._get_settings(**new_settings)
class DummyPolicyTest(_BaseTest):
policy_class = 'scrapy.extensions.httpcache.DummyPolicy'
def test_middleware(self):
with self._middleware() as mw:
assert mw.process_request(self.request, self.spider) is None
mw.process_response(self.request, self.response, self.spider)
response = mw.process_request(self.request, self.spider)
assert isinstance(response, HtmlResponse)
self.assertEqualResponse(self.response, response)
assert 'cached' in response.flags
def test_different_request_response_urls(self):
with self._middleware() as mw:
req = Request('http://host.com/path')
res = Response('http://host2.net/test.html')
assert mw.process_request(req, self.spider) is None
mw.process_response(req, res, self.spider)
cached = mw.process_request(req, self.spider)
assert isinstance(cached, Response)
self.assertEqualResponse(res, cached)
assert 'cached' in cached.flags
def test_middleware_ignore_missing(self):
with self._middleware(HTTPCACHE_IGNORE_MISSING=True) as mw:
self.assertRaises(IgnoreRequest, mw.process_request, self.request, self.spider)
mw.process_response(self.request, self.response, self.spider)
response = mw.process_request(self.request, self.spider)
assert isinstance(response, HtmlResponse)
self.assertEqualResponse(self.response, response)
assert 'cached' in response.flags
def test_middleware_ignore_schemes(self):
# http responses are cached by default
req, res = Request('http://test.com/'), Response('http://test.com/')
with self._middleware() as mw:
assert mw.process_request(req, self.spider) is None
mw.process_response(req, res, self.spider)
cached = mw.process_request(req, self.spider)
assert isinstance(cached, Response), type(cached)
self.assertEqualResponse(res, cached)
assert 'cached' in cached.flags
# file response is not cached by default
req, res = Request('file:///tmp/t.txt'), Response('file:///tmp/t.txt')
with self._middleware() as mw:
assert mw.process_request(req, self.spider) is None
mw.process_response(req, res, self.spider)
assert mw.storage.retrieve_response(self.spider, req) is None
assert mw.process_request(req, self.spider) is None
# s3 scheme response is cached by default
req, res = Request('s3://bucket/key'), Response('http://bucket/key')
with self._middleware() as mw:
assert mw.process_request(req, self.spider) is None
mw.process_response(req, res, self.spider)
cached = mw.process_request(req, self.spider)
assert isinstance(cached, Response), type(cached)
self.assertEqualResponse(res, cached)
assert 'cached' in cached.flags
# ignore s3 scheme
req, res = Request('s3://bucket/key2'), Response('http://bucket/key2')
with self._middleware(HTTPCACHE_IGNORE_SCHEMES=['s3']) as mw:
assert mw.process_request(req, self.spider) is None
mw.process_response(req, res, self.spider)
assert mw.storage.retrieve_response(self.spider, req) is None
assert mw.process_request(req, self.spider) is None
def test_middleware_ignore_http_codes(self):
# test response is not cached
with self._middleware(HTTPCACHE_IGNORE_HTTP_CODES=[202]) as mw:
assert mw.process_request(self.request, self.spider) is None
mw.process_response(self.request, self.response, self.spider)
assert mw.storage.retrieve_response(self.spider, self.request) is None
assert mw.process_request(self.request, self.spider) is None
# test response is cached
with self._middleware(HTTPCACHE_IGNORE_HTTP_CODES=[203]) as mw:
mw.process_response(self.request, self.response, self.spider)
response = mw.process_request(self.request, self.spider)
assert isinstance(response, HtmlResponse)
self.assertEqualResponse(self.response, response)
assert 'cached' in response.flags
class RFC2616PolicyTest(DefaultStorageTest):
policy_class = 'scrapy.extensions.httpcache.RFC2616Policy'
def _process_requestresponse(self, mw, request, response):
result = None
try:
result = mw.process_request(request, self.spider)
if result:
assert isinstance(result, (Request, Response))
return result
else:
result = mw.process_response(request, response, self.spider)
assert isinstance(result, Response)
return result
except Exception:
print('Request', request)
print('Response', response)
print('Result', result)
raise
def test_request_cacheability(self):
res0 = Response(self.request.url, status=200,
headers={'Expires': self.tomorrow})
req0 = Request('http://example.com')
req1 = req0.replace(headers={'Cache-Control': 'no-store'})
req2 = req0.replace(headers={'Cache-Control': 'no-cache'})
with self._middleware() as mw:
# response for a request with no-store must not be cached
res1 = self._process_requestresponse(mw, req1, res0)
self.assertEqualResponse(res1, res0)
assert mw.storage.retrieve_response(self.spider, req1) is None
# Re-do request without no-store and expect it to be cached
res2 = self._process_requestresponse(mw, req0, res0)
assert 'cached' not in res2.flags
res3 = mw.process_request(req0, self.spider)
assert 'cached' in res3.flags
self.assertEqualResponse(res2, res3)
# request with no-cache directive must not return cached response
# but it allows new response to be stored
res0b = res0.replace(body=b'foo')
res4 = self._process_requestresponse(mw, req2, res0b)
self.assertEqualResponse(res4, res0b)
assert 'cached' not in res4.flags
res5 = self._process_requestresponse(mw, req0, None)
self.assertEqualResponse(res5, res0b)
assert 'cached' in res5.flags
def test_response_cacheability(self):
responses = [
# 304 is not cacheable no matter what servers sends
(False, 304, {}),
(False, 304, {'Last-Modified': self.yesterday}),
(False, 304, {'Expires': self.tomorrow}),
(False, 304, {'Etag': 'bar'}),
(False, 304, {'Cache-Control': 'max-age=3600'}),
# Always obey no-store cache control
(False, 200, {'Cache-Control': 'no-store'}),
(False, 200, {'Cache-Control': 'no-store, max-age=300'}), # invalid
(False, 200, {'Cache-Control': 'no-store', 'Expires': self.tomorrow}), # invalid
# Ignore responses missing expiration and/or validation headers
(False, 200, {}),
(False, 302, {}),
(False, 307, {}),
(False, 404, {}),
# Cache responses with expiration and/or validation headers
(True, 200, {'Last-Modified': self.yesterday}),
(True, 203, {'Last-Modified': self.yesterday}),
(True, 300, {'Last-Modified': self.yesterday}),
(True, 301, {'Last-Modified': self.yesterday}),
(True, 308, {'Last-Modified': self.yesterday}),
(True, 401, {'Last-Modified': self.yesterday}),
(True, 404, {'Cache-Control': 'public, max-age=600'}),
(True, 302, {'Expires': self.tomorrow}),
(True, 200, {'Etag': 'foo'}),
]
with self._middleware() as mw:
for idx, (shouldcache, status, headers) in enumerate(responses):
req0 = Request(f'http://example-{idx}.com')
res0 = Response(req0.url, status=status, headers=headers)
res1 = self._process_requestresponse(mw, req0, res0)
res304 = res0.replace(status=304)
res2 = self._process_requestresponse(mw, req0, res304 if shouldcache else res0)
self.assertEqualResponse(res1, res0)
self.assertEqualResponse(res2, res0)
resc = mw.storage.retrieve_response(self.spider, req0)
if shouldcache:
self.assertEqualResponse(resc, res1)
assert 'cached' in res2.flags and res2.status != 304
else:
self.assertFalse(resc)
assert 'cached' not in res2.flags
# cache unconditionally unless response contains no-store or is a 304
with self._middleware(HTTPCACHE_ALWAYS_STORE=True) as mw:
for idx, (_, status, headers) in enumerate(responses):
shouldcache = 'no-store' not in headers.get('Cache-Control', '') and status != 304
req0 = Request(f'http://example2-{idx}.com')
res0 = Response(req0.url, status=status, headers=headers)
res1 = self._process_requestresponse(mw, req0, res0)
res304 = res0.replace(status=304)
res2 = self._process_requestresponse(mw, req0, res304 if shouldcache else res0)
self.assertEqualResponse(res1, res0)
self.assertEqualResponse(res2, res0)
resc = mw.storage.retrieve_response(self.spider, req0)
if shouldcache:
self.assertEqualResponse(resc, res1)
assert 'cached' in res2.flags and res2.status != 304
else:
self.assertFalse(resc)
assert 'cached' not in res2.flags
def test_cached_and_fresh(self):
sampledata = [
(200, {'Date': self.yesterday, 'Expires': self.tomorrow}),
(200, {'Date': self.yesterday, 'Cache-Control': 'max-age=86405'}),
(200, {'Age': '299', 'Cache-Control': 'max-age=300'}),
# Obey max-age if present over any others
(200, {'Date': self.today,
'Age': '86405',
'Cache-Control': 'max-age=' + str(86400 * 3),
'Expires': self.yesterday,
'Last-Modified': self.yesterday,
}),
# obey Expires if max-age is not present
(200, {'Date': self.yesterday,
'Age': '86400',
'Cache-Control': 'public',
'Expires': self.tomorrow,
'Last-Modified': self.yesterday,
}),
# Default missing Date header to right now
(200, {'Expires': self.tomorrow}),
# Firefox - Expires if age is greater than 10% of (Date - Last-Modified)
(200, {'Date': self.today, 'Last-Modified': self.yesterday, 'Age': str(86400 / 10 - 1)}),
# Firefox - Set one year maxage to permanent redirects missing expiration info
(300, {}), (301, {}), (308, {}),
]
with self._middleware() as mw:
for idx, (status, headers) in enumerate(sampledata):
req0 = Request(f'http://example-{idx}.com')
res0 = Response(req0.url, status=status, headers=headers)
# cache fresh response
res1 = self._process_requestresponse(mw, req0, res0)
self.assertEqualResponse(res1, res0)
assert 'cached' not in res1.flags
# return fresh cached response without network interaction
res2 = self._process_requestresponse(mw, req0, None)
self.assertEqualResponse(res1, res2)
assert 'cached' in res2.flags
# validate cached response if request max-age set as 0
req1 = req0.replace(headers={'Cache-Control': 'max-age=0'})
res304 = res0.replace(status=304)
assert mw.process_request(req1, self.spider) is None
res3 = self._process_requestresponse(mw, req1, res304)
self.assertEqualResponse(res1, res3)
assert 'cached' in res3.flags
def test_cached_and_stale(self):
sampledata = [
(200, {'Date': self.today, 'Expires': self.yesterday}),
(200, {'Date': self.today, 'Expires': self.yesterday, 'Last-Modified': self.yesterday}),
(200, {'Expires': self.yesterday}),
(200, {'Expires': self.yesterday, 'ETag': 'foo'}),
(200, {'Expires': self.yesterday, 'Last-Modified': self.yesterday}),
(200, {'Expires': self.tomorrow, 'Age': '86405'}),
(200, {'Cache-Control': 'max-age=86400', 'Age': '86405'}),
# no-cache forces expiration, also revalidation if validators exists
(200, {'Cache-Control': 'no-cache'}),
(200, {'Cache-Control': 'no-cache', 'ETag': 'foo'}),
(200, {'Cache-Control': 'no-cache', 'Last-Modified': self.yesterday}),
(200, {'Cache-Control': 'no-cache,must-revalidate', 'Last-Modified': self.yesterday}),
(200, {'Cache-Control': 'must-revalidate', 'Expires': self.yesterday, 'Last-Modified': self.yesterday}),
(200, {'Cache-Control': 'max-age=86400,must-revalidate', 'Age': '86405'}),
]
with self._middleware() as mw:
for idx, (status, headers) in enumerate(sampledata):
req0 = Request(f'http://example-{idx}.com')
res0a = Response(req0.url, status=status, headers=headers)
# cache expired response
res1 = self._process_requestresponse(mw, req0, res0a)
self.assertEqualResponse(res1, res0a)
assert 'cached' not in res1.flags
# Same request but as cached response is stale a new response must
# be returned
res0b = res0a.replace(body=b'bar')
res2 = self._process_requestresponse(mw, req0, res0b)
self.assertEqualResponse(res2, res0b)
assert 'cached' not in res2.flags
cc = headers.get('Cache-Control', '')
# Previous response expired too, subsequent request to same
# resource must revalidate and succeed on 304 if validators
# are present
if 'ETag' in headers or 'Last-Modified' in headers:
res0c = res0b.replace(status=304)
res3 = self._process_requestresponse(mw, req0, res0c)
self.assertEqualResponse(res3, res0b)
assert 'cached' in res3.flags
# get cached response on server errors unless must-revalidate
# in cached response
res0d = res0b.replace(status=500)
res4 = self._process_requestresponse(mw, req0, res0d)
if 'must-revalidate' in cc:
assert 'cached' not in res4.flags
self.assertEqualResponse(res4, res0d)
else:
assert 'cached' in res4.flags
self.assertEqualResponse(res4, res0b)
# Requests with max-stale can fetch expired cached responses
# unless cached response has must-revalidate
req1 = req0.replace(headers={'Cache-Control': 'max-stale'})
res5 = self._process_requestresponse(mw, req1, res0b)
self.assertEqualResponse(res5, res0b)
if 'no-cache' in cc or 'must-revalidate' in cc:
assert 'cached' not in res5.flags
else:
assert 'cached' in res5.flags
def test_process_exception(self):
with self._middleware() as mw:
res0 = Response(self.request.url, headers={'Expires': self.yesterday})
req0 = Request(self.request.url)
self._process_requestresponse(mw, req0, res0)
for e in mw.DOWNLOAD_EXCEPTIONS:
# Simulate encountering an error on download attempts
assert mw.process_request(req0, self.spider) is None
res1 = mw.process_exception(req0, e('foo'), self.spider)
# Use cached response as recovery
assert 'cached' in res1.flags
self.assertEqualResponse(res0, res1)
# Do not use cached response for unhandled exceptions
mw.process_request(req0, self.spider)
assert mw.process_exception(req0, Exception('foo'), self.spider) is None
def test_ignore_response_cache_controls(self):
sampledata = [
(200, {'Date': self.yesterday, 'Expires': self.tomorrow}),
(200, {'Date': self.yesterday, 'Cache-Control': 'no-store,max-age=86405'}),
(200, {'Age': '299', 'Cache-Control': 'max-age=300,no-cache'}),
(300, {'Cache-Control': 'no-cache'}),
(200, {'Expires': self.tomorrow, 'Cache-Control': 'no-store'}),
]
with self._middleware(HTTPCACHE_IGNORE_RESPONSE_CACHE_CONTROLS=['no-cache', 'no-store']) as mw:
for idx, (status, headers) in enumerate(sampledata):
req0 = Request(f'http://example-{idx}.com')
res0 = Response(req0.url, status=status, headers=headers)
# cache fresh response
res1 = self._process_requestresponse(mw, req0, res0)
self.assertEqualResponse(res1, res0)
assert 'cached' not in res1.flags
# return fresh cached response without network interaction
res2 = self._process_requestresponse(mw, req0, None)
self.assertEqualResponse(res1, res2)
assert 'cached' in res2.flags
if __name__ == '__main__':
unittest.main()