sdk/python/tests/test_keep_client.py

   1 import hashlib
   2 import mock
   3 import os
   4 import random
   5 import re
   6 import socket
   7 import unittest
   8 import urlparse
   9
  10 import arvados
  11 import arvados.retry
  12 import arvados_testutil as tutil
  13 import run_test_server
  14
  15 class KeepTestCase(run_test_server.TestCaseWithServers):
  16     MAIN_SERVER = {}
  17     KEEP_SERVER = {}
  18
  19     @classmethod
  20     def setUpClass(cls):
  21         super(KeepTestCase, cls).setUpClass()
  22         run_test_server.authorize_with("admin")
  23         cls.api_client = arvados.api('v1')
  24         cls.keep_client = arvados.KeepClient(api_client=cls.api_client,
  25                                              proxy='', local_store='')
  26
  27     def test_KeepBasicRWTest(self):
  28         foo_locator = self.keep_client.put('foo')
  29         self.assertRegexpMatches(
  30             foo_locator,
  31             '^acbd18db4cc2f85cedef654fccc4a4d8\+3',
  32             'wrong md5 hash from Keep.put("foo"): ' + foo_locator)
  33         self.assertEqual(self.keep_client.get(foo_locator),
  34                          'foo',
  35                          'wrong content from Keep.get(md5("foo"))')
  36
  37     def test_KeepBinaryRWTest(self):
  38         blob_str = '\xff\xfe\xf7\x00\x01\x02'
  39         blob_locator = self.keep_client.put(blob_str)
  40         self.assertRegexpMatches(
  41             blob_locator,
  42             '^7fc7c53b45e53926ba52821140fef396\+6',
  43             ('wrong locator from Keep.put(<binarydata>):' + blob_locator))
  44         self.assertEqual(self.keep_client.get(blob_locator),
  45                          blob_str,
  46                          'wrong content from Keep.get(md5(<binarydata>))')
  47
  48     def test_KeepLongBinaryRWTest(self):
  49         blob_str = '\xff\xfe\xfd\xfc\x00\x01\x02\x03'
  50         for i in range(0,23):
  51             blob_str = blob_str + blob_str
  52         blob_locator = self.keep_client.put(blob_str)
  53         self.assertRegexpMatches(
  54             blob_locator,
  55             '^84d90fc0d8175dd5dcfab04b999bc956\+67108864',
  56             ('wrong locator from Keep.put(<binarydata>): ' + blob_locator))
  57         self.assertEqual(self.keep_client.get(blob_locator),
  58                          blob_str,
  59                          'wrong content from Keep.get(md5(<binarydata>))')
  60
  61     def test_KeepSingleCopyRWTest(self):
  62         blob_str = '\xff\xfe\xfd\xfc\x00\x01\x02\x03'
  63         blob_locator = self.keep_client.put(blob_str, copies=1)
  64         self.assertRegexpMatches(
  65             blob_locator,
  66             '^c902006bc98a3eb4a3663b65ab4a6fab\+8',
  67             ('wrong locator from Keep.put(<binarydata>): ' + blob_locator))
  68         self.assertEqual(self.keep_client.get(blob_locator),
  69                          blob_str,
  70                          'wrong content from Keep.get(md5(<binarydata>))')
  71
  72     def test_KeepEmptyCollectionTest(self):
  73         blob_locator = self.keep_client.put('', copies=1)
  74         self.assertRegexpMatches(
  75             blob_locator,
  76             '^d41d8cd98f00b204e9800998ecf8427e\+0',
  77             ('wrong locator from Keep.put(""): ' + blob_locator))
  78
  79
  80 class KeepPermissionTestCase(run_test_server.TestCaseWithServers):
  81     MAIN_SERVER = {}
  82     KEEP_SERVER = {'blob_signing_key': 'abcdefghijk0123456789',
  83                    'enforce_permissions': True}
  84
  85     def test_KeepBasicRWTest(self):
  86         run_test_server.authorize_with('active')
  87         keep_client = arvados.KeepClient()
  88         foo_locator = keep_client.put('foo')
  89         self.assertRegexpMatches(
  90             foo_locator,
  91             r'^acbd18db4cc2f85cedef654fccc4a4d8\+3\+A[a-f0-9]+@[a-f0-9]+$',
  92             'invalid locator from Keep.put("foo"): ' + foo_locator)
  93         self.assertEqual(keep_client.get(foo_locator),
  94                          'foo',
  95                          'wrong content from Keep.get(md5("foo"))')
  96
  97         # GET with an unsigned locator => NotFound
  98         bar_locator = keep_client.put('bar')
  99         unsigned_bar_locator = "37b51d194a7513e45b56f6524f2d51f2+3"
 100         self.assertRegexpMatches(
 101             bar_locator,
 102             r'^37b51d194a7513e45b56f6524f2d51f2\+3\+A[a-f0-9]+@[a-f0-9]+$',
 103             'invalid locator from Keep.put("bar"): ' + bar_locator)
 104         self.assertRaises(arvados.errors.NotFoundError,
 105                           keep_client.get,
 106                           unsigned_bar_locator)
 107
 108         # GET from a different user => NotFound
 109         run_test_server.authorize_with('spectator')
 110         self.assertRaises(arvados.errors.NotFoundError,
 111                           arvados.Keep.get,
 112                           bar_locator)
 113
 114         # Unauthenticated GET for a signed locator => NotFound
 115         # Unauthenticated GET for an unsigned locator => NotFound
 116         keep_client.api_token = ''
 117         self.assertRaises(arvados.errors.NotFoundError,
 118                           keep_client.get,
 119                           bar_locator)
 120         self.assertRaises(arvados.errors.NotFoundError,
 121                           keep_client.get,
 122                           unsigned_bar_locator)
 123
 124
 125 # KeepOptionalPermission: starts Keep with --permission-key-file
 126 # but not --enforce-permissions (i.e. generate signatures on PUT
 127 # requests, but do not require them for GET requests)
 128 #
 129 # All of these requests should succeed when permissions are optional:
 130 # * authenticated request, signed locator
 131 # * authenticated request, unsigned locator
 132 # * unauthenticated request, signed locator
 133 # * unauthenticated request, unsigned locator
 134 class KeepOptionalPermission(run_test_server.TestCaseWithServers):
 135     MAIN_SERVER = {}
 136     KEEP_SERVER = {'blob_signing_key': 'abcdefghijk0123456789',
 137                    'enforce_permissions': False}
 138
 139     @classmethod
 140     def setUpClass(cls):
 141         super(KeepOptionalPermission, cls).setUpClass()
 142         run_test_server.authorize_with("admin")
 143         cls.api_client = arvados.api('v1')
 144
 145     def setUp(self):
 146         super(KeepOptionalPermission, self).setUp()
 147         self.keep_client = arvados.KeepClient(api_client=self.api_client,
 148                                               proxy='', local_store='')
 149
 150     def _put_foo_and_check(self):
 151         signed_locator = self.keep_client.put('foo')
 152         self.assertRegexpMatches(
 153             signed_locator,
 154             r'^acbd18db4cc2f85cedef654fccc4a4d8\+3\+A[a-f0-9]+@[a-f0-9]+$',
 155             'invalid locator from Keep.put("foo"): ' + signed_locator)
 156         return signed_locator
 157
 158     def test_KeepAuthenticatedSignedTest(self):
 159         signed_locator = self._put_foo_and_check()
 160         self.assertEqual(self.keep_client.get(signed_locator),
 161                          'foo',
 162                          'wrong content from Keep.get(md5("foo"))')
 163
 164     def test_KeepAuthenticatedUnsignedTest(self):
 165         signed_locator = self._put_foo_and_check()
 166         self.assertEqual(self.keep_client.get("acbd18db4cc2f85cedef654fccc4a4d8"),
 167                          'foo',
 168                          'wrong content from Keep.get(md5("foo"))')
 169
 170     def test_KeepUnauthenticatedSignedTest(self):
 171         # Check that signed GET requests work even when permissions
 172         # enforcement is off.
 173         signed_locator = self._put_foo_and_check()
 174         self.keep_client.api_token = ''
 175         self.assertEqual(self.keep_client.get(signed_locator),
 176                          'foo',
 177                          'wrong content from Keep.get(md5("foo"))')
 178
 179     def test_KeepUnauthenticatedUnsignedTest(self):
 180         # Since --enforce-permissions is not in effect, GET requests
 181         # need not be authenticated.
 182         signed_locator = self._put_foo_and_check()
 183         self.keep_client.api_token = ''
 184         self.assertEqual(self.keep_client.get("acbd18db4cc2f85cedef654fccc4a4d8"),
 185                          'foo',
 186                          'wrong content from Keep.get(md5("foo"))')
 187
 188
 189 class KeepProxyTestCase(run_test_server.TestCaseWithServers):
 190     MAIN_SERVER = {}
 191     KEEP_SERVER = {}
 192     KEEP_PROXY_SERVER = {'auth': 'admin'}
 193
 194     @classmethod
 195     def setUpClass(cls):
 196         super(KeepProxyTestCase, cls).setUpClass()
 197         cls.api_client = arvados.api('v1')
 198
 199     def tearDown(self):
 200         arvados.config.settings().pop('ARVADOS_EXTERNAL_CLIENT', None)
 201         super(KeepProxyTestCase, self).tearDown()
 202
 203     def test_KeepProxyTest1(self):
 204         # Will use ARVADOS_KEEP_PROXY environment variable that is set by
 205         # setUpClass().
 206         keep_client = arvados.KeepClient(api_client=self.api_client,
 207                                          local_store='')
 208         baz_locator = keep_client.put('baz')
 209         self.assertRegexpMatches(
 210             baz_locator,
 211             '^73feffa4b7f6bb68e44cf984c85f6e88\+3',
 212             'wrong md5 hash from Keep.put("baz"): ' + baz_locator)
 213         self.assertEqual(keep_client.get(baz_locator),
 214                          'baz',
 215                          'wrong content from Keep.get(md5("baz"))')
 216         self.assertTrue(keep_client.using_proxy)
 217
 218     def test_KeepProxyTest2(self):
 219         # Don't instantiate the proxy directly, but set the X-External-Client
 220         # header.  The API server should direct us to the proxy.
 221         arvados.config.settings()['ARVADOS_EXTERNAL_CLIENT'] = 'true'
 222         keep_client = arvados.KeepClient(api_client=self.api_client,
 223                                          proxy='', local_store='')
 224         baz_locator = keep_client.put('baz2')
 225         self.assertRegexpMatches(
 226             baz_locator,
 227             '^91f372a266fe2bf2823cb8ec7fda31ce\+4',
 228             'wrong md5 hash from Keep.put("baz2"): ' + baz_locator)
 229         self.assertEqual(keep_client.get(baz_locator),
 230                          'baz2',
 231                          'wrong content from Keep.get(md5("baz2"))')
 232         self.assertTrue(keep_client.using_proxy)
 233
 234
 235 class KeepClientServiceTestCase(unittest.TestCase, tutil.ApiClientMock):
 236     def get_service_roots(self, api_client):
 237         keep_client = arvados.KeepClient(api_client=api_client)
 238         services = keep_client.weighted_service_roots('000000')
 239         return [urlparse.urlparse(url) for url in sorted(services)]
 240
 241     def test_ssl_flag_respected_in_roots(self):
 242         for ssl_flag in [False, True]:
 243             services = self.get_service_roots(self.mock_keep_services(
 244                 service_ssl_flag=ssl_flag))
 245             self.assertEqual(
 246                 ('https' if ssl_flag else 'http'), services[0].scheme)
 247
 248     def test_correct_ports_with_ipv6_addresses(self):
 249         service = self.get_service_roots(self.mock_keep_services(
 250             service_type='proxy', service_host='100::1', service_port=10, count=1))[0]
 251         self.assertEqual('100::1', service.hostname)
 252         self.assertEqual(10, service.port)
 253
 254     # test_get_timeout and test_put_timeout test that
 255     # KeepClient.get and KeepClient.put use the appropriate timeouts
 256     # when connected directly to a Keep server (i.e. non-proxy timeout)
 257
 258     def test_get_timeout(self):
 259         api_client = self.mock_keep_services(count=1)
 260         keep_client = arvados.KeepClient(api_client=api_client)
 261         force_timeout = [socket.timeout("timed out")]
 262         with mock.patch('requests.get', side_effect=force_timeout) as mock_request:
 263             with self.assertRaises(arvados.errors.KeepReadError):
 264                 keep_client.get('ffffffffffffffffffffffffffffffff')
 265             self.assertTrue(mock_request.called)
 266             self.assertEqual(
 267                 arvados.KeepClient.DEFAULT_TIMEOUT,
 268                 mock_request.call_args[1]['timeout'])
 269
 270     def test_put_timeout(self):
 271         api_client = self.mock_keep_services(count=1)
 272         keep_client = arvados.KeepClient(api_client=api_client)
 273         force_timeout = [socket.timeout("timed out")]
 274         with mock.patch('requests.put', side_effect=force_timeout) as mock_request:
 275             with self.assertRaises(arvados.errors.KeepWriteError):
 276                 keep_client.put('foo')
 277             self.assertTrue(mock_request.called)
 278             self.assertEqual(
 279                 arvados.KeepClient.DEFAULT_TIMEOUT,
 280                 mock_request.call_args[1]['timeout'])
 281
 282     def test_proxy_get_timeout(self):
 283         # Force a timeout, verifying that the requests.get or
 284         # requests.put method was called with the proxy_timeout
 285         # setting rather than the default timeout.
 286         api_client = self.mock_keep_services(service_type='proxy', count=1)
 287         keep_client = arvados.KeepClient(api_client=api_client)
 288         force_timeout = [socket.timeout("timed out")]
 289         with mock.patch('requests.get', side_effect=force_timeout) as mock_request:
 290             with self.assertRaises(arvados.errors.KeepReadError):
 291                 keep_client.get('ffffffffffffffffffffffffffffffff')
 292             self.assertTrue(mock_request.called)
 293             self.assertEqual(
 294                 arvados.KeepClient.DEFAULT_PROXY_TIMEOUT,
 295                 mock_request.call_args[1]['timeout'])
 296
 297     def test_proxy_put_timeout(self):
 298         # Force a timeout, verifying that the requests.get or
 299         # requests.put method was called with the proxy_timeout
 300         # setting rather than the default timeout.
 301         api_client = self.mock_keep_services(service_type='proxy', count=1)
 302         keep_client = arvados.KeepClient(api_client=api_client)
 303         force_timeout = [socket.timeout("timed out")]
 304         with mock.patch('requests.put', side_effect=force_timeout) as mock_request:
 305             with self.assertRaises(arvados.errors.KeepWriteError):
 306                 keep_client.put('foo')
 307             self.assertTrue(mock_request.called)
 308             self.assertEqual(
 309                 arvados.KeepClient.DEFAULT_PROXY_TIMEOUT,
 310                 mock_request.call_args[1]['timeout'])
 311
 312     def test_probe_order_reference_set(self):
 313         # expected_order[i] is the probe order for
 314         # hash=md5(sprintf("%064x",i)) where there are 16 services
 315         # with uuid sprintf("anything-%015x",j) with j in 0..15. E.g.,
 316         # the first probe for the block consisting of 64 "0"
 317         # characters is the service whose uuid is
 318         # "zzzzz-bi6l4-000000000000003", so expected_order[0][0]=='3'.
 319         expected_order = [
 320             list('3eab2d5fc9681074'),
 321             list('097dba52e648f1c3'),
 322             list('c5b4e023f8a7d691'),
 323             list('9d81c02e76a3bf54'),
 324             ]
 325         hashes = [
 326             hashlib.md5("{:064x}".format(x)).hexdigest()
 327             for x in range(len(expected_order))]
 328         api_client = self.mock_keep_services(count=16)
 329         keep_client = arvados.KeepClient(api_client=api_client)
 330         for i, hash in enumerate(hashes):
 331             roots = keep_client.weighted_service_roots(hash)
 332             got_order = [
 333                 re.search(r'//\[?keep0x([0-9a-f]+)', root).group(1)
 334                 for root in roots]
 335             self.assertEqual(expected_order[i], got_order)
 336
 337     def test_probe_waste_adding_one_server(self):
 338         hashes = [
 339             hashlib.md5("{:064x}".format(x)).hexdigest() for x in range(100)]
 340         initial_services = 12
 341         api_client = self.mock_keep_services(count=initial_services)
 342         keep_client = arvados.KeepClient(api_client=api_client)
 343         probes_before = [
 344             keep_client.weighted_service_roots(hash) for hash in hashes]
 345         for added_services in range(1, 12):
 346             api_client = self.mock_keep_services(count=initial_services+added_services)
 347             keep_client = arvados.KeepClient(api_client=api_client)
 348             total_penalty = 0
 349             for hash_index in range(len(hashes)):
 350                 probe_after = keep_client.weighted_service_roots(
 351                     hashes[hash_index])
 352                 penalty = probe_after.index(probes_before[hash_index][0])
 353                 self.assertLessEqual(penalty, added_services)
 354                 total_penalty += penalty
 355             # Average penalty per block should not exceed
 356             # N(added)/N(orig) by more than 20%, and should get closer
 357             # to the ideal as we add data points.
 358             expect_penalty = (
 359                 added_services *
 360                 len(hashes) / initial_services)
 361             max_penalty = (
 362                 expect_penalty *
 363                 (120 - added_services)/100)
 364             min_penalty = (
 365                 expect_penalty * 8/10)
 366             self.assertTrue(
 367                 min_penalty <= total_penalty <= max_penalty,
 368                 "With {}+{} services, {} blocks, penalty {} but expected {}..{}".format(
 369                     initial_services,
 370                     added_services,
 371                     len(hashes),
 372                     total_penalty,
 373                     min_penalty,
 374                     max_penalty))
 375
 376     def check_64_zeros_error_order(self, verb, exc_class):
 377         data = '0' * 64
 378         if verb == 'get':
 379             data = hashlib.md5(data).hexdigest() + '+1234'
 380         # Arbitrary port number:
 381         aport = random.randint(1024,65535)
 382         api_client = self.mock_keep_services(service_port=aport, count=16)
 383         keep_client = arvados.KeepClient(api_client=api_client)
 384         with mock.patch('requests.' + verb,
 385                         side_effect=socket.timeout) as req_mock, \
 386                 self.assertRaises(exc_class) as err_check:
 387             getattr(keep_client, verb)(data)
 388         urls = [urlparse.urlparse(url)
 389                 for url in err_check.exception.service_errors()]
 390         self.assertEqual([('keep0x' + c, aport) for c in '3eab2d5fc9681074'],
 391                          [(url.hostname, url.port) for url in urls])
 392
 393     def test_get_error_shows_probe_order(self):
 394         self.check_64_zeros_error_order('get', arvados.errors.KeepReadError)
 395
 396     def test_put_error_shows_probe_order(self):
 397         self.check_64_zeros_error_order('put', arvados.errors.KeepWriteError)
 398
 399     def check_no_services_error(self, verb, exc_class):
 400         api_client = mock.MagicMock(name='api_client')
 401         api_client.keep_services().accessible().execute.side_effect = (
 402             arvados.errors.ApiError)
 403         keep_client = arvados.KeepClient(api_client=api_client)
 404         with self.assertRaises(exc_class) as err_check:
 405             getattr(keep_client, verb)('d41d8cd98f00b204e9800998ecf8427e+0')
 406         self.assertEqual(0, len(err_check.exception.service_errors()))
 407
 408     def test_get_error_with_no_services(self):
 409         self.check_no_services_error('get', arvados.errors.KeepReadError)
 410
 411     def test_put_error_with_no_services(self):
 412         self.check_no_services_error('put', arvados.errors.KeepWriteError)
 413
 414     def check_errors_from_last_retry(self, verb, exc_class):
 415         api_client = self.mock_keep_services(count=2)
 416         keep_client = arvados.KeepClient(api_client=api_client)
 417         req_mock = getattr(tutil, 'mock_{}_responses'.format(verb))(
 418             "retry error reporting test", 500, 500, 403, 403)
 419         with req_mock, tutil.skip_sleep, \
 420                 self.assertRaises(exc_class) as err_check:
 421             getattr(keep_client, verb)('d41d8cd98f00b204e9800998ecf8427e+0',
 422                                        num_retries=3)
 423         self.assertEqual([403, 403], [
 424                 getattr(error, 'status_code', None)
 425                 for error in err_check.exception.service_errors().itervalues()])
 426
 427     def test_get_error_reflects_last_retry(self):
 428         self.check_errors_from_last_retry('get', arvados.errors.KeepReadError)
 429
 430     def test_put_error_reflects_last_retry(self):
 431         self.check_errors_from_last_retry('put', arvados.errors.KeepWriteError)
 432
 433     def test_put_error_does_not_include_successful_puts(self):
 434         data = 'partial failure test'
 435         data_loc = '{}+{}'.format(hashlib.md5(data).hexdigest(), len(data))
 436         api_client = self.mock_keep_services(count=3)
 437         keep_client = arvados.KeepClient(api_client=api_client)
 438         with tutil.mock_put_responses(data_loc, 200, 500, 500) as req_mock, \
 439                 self.assertRaises(arvados.errors.KeepWriteError) as exc_check:
 440             keep_client.put(data)
 441         self.assertEqual(2, len(exc_check.exception.service_errors()))
 442
 443
 444 class KeepClientRetryTestMixin(object):
 445     # Testing with a local Keep store won't exercise the retry behavior.
 446     # Instead, our strategy is:
 447     # * Create a client with one proxy specified (pointed at a black
 448     #   hole), so there's no need to instantiate an API client, and
 449     #   all HTTP requests come from one place.
 450     # * Mock httplib's request method to provide simulated responses.
 451     # This lets us test the retry logic extensively without relying on any
 452     # supporting servers, and prevents side effects in case something hiccups.
 453     # To use this mixin, define DEFAULT_EXPECT, DEFAULT_EXCEPTION, and
 454     # run_method().
 455     #
 456     # Test classes must define TEST_PATCHER to a method that mocks
 457     # out appropriate methods in the client.
 458
 459     PROXY_ADDR = 'http://[%s]:65535/' % (tutil.TEST_HOST,)
 460     TEST_DATA = 'testdata'
 461     TEST_LOCATOR = 'ef654c40ab4f1747fc699915d4f70902+8'
 462
 463     def setUp(self):
 464         self.client_kwargs = {'proxy': self.PROXY_ADDR, 'local_store': ''}
 465
 466     def new_client(self, **caller_kwargs):
 467         kwargs = self.client_kwargs.copy()
 468         kwargs.update(caller_kwargs)
 469         return arvados.KeepClient(**kwargs)
 470
 471     def run_method(self, *args, **kwargs):
 472         raise NotImplementedError("test subclasses must define run_method")
 473
 474     def check_success(self, expected=None, *args, **kwargs):
 475         if expected is None:
 476             expected = self.DEFAULT_EXPECT
 477         self.assertEqual(expected, self.run_method(*args, **kwargs))
 478
 479     def check_exception(self, error_class=None, *args, **kwargs):
 480         if error_class is None:
 481             error_class = self.DEFAULT_EXCEPTION
 482         self.assertRaises(error_class, self.run_method, *args, **kwargs)
 483
 484     def test_immediate_success(self):
 485         with self.TEST_PATCHER(self.DEFAULT_EXPECT, 200):
 486             self.check_success()
 487
 488     def test_retry_then_success(self):
 489         with self.TEST_PATCHER(self.DEFAULT_EXPECT, 500, 200):
 490             self.check_success(num_retries=3)
 491
 492     def test_no_default_retry(self):
 493         with self.TEST_PATCHER(self.DEFAULT_EXPECT, 500, 200):
 494             self.check_exception()
 495
 496     def test_no_retry_after_permanent_error(self):
 497         with self.TEST_PATCHER(self.DEFAULT_EXPECT, 403, 200):
 498             self.check_exception(num_retries=3)
 499
 500     def test_error_after_retries_exhausted(self):
 501         with self.TEST_PATCHER(self.DEFAULT_EXPECT, 500, 500, 200):
 502             self.check_exception(num_retries=1)
 503
 504     def test_num_retries_instance_fallback(self):
 505         self.client_kwargs['num_retries'] = 3
 506         with self.TEST_PATCHER(self.DEFAULT_EXPECT, 500, 200):
 507             self.check_success()
 508
 509
 510 @tutil.skip_sleep
 511 class KeepClientRetryGetTestCase(KeepClientRetryTestMixin, unittest.TestCase):
 512     DEFAULT_EXPECT = KeepClientRetryTestMixin.TEST_DATA
 513     DEFAULT_EXCEPTION = arvados.errors.KeepReadError
 514     HINTED_LOCATOR = KeepClientRetryTestMixin.TEST_LOCATOR + '+K@xyzzy'
 515     TEST_PATCHER = staticmethod(tutil.mock_get_responses)
 516
 517     def run_method(self, locator=KeepClientRetryTestMixin.TEST_LOCATOR,
 518                    *args, **kwargs):
 519         return self.new_client().get(locator, *args, **kwargs)
 520
 521     def test_specific_exception_when_not_found(self):
 522         with tutil.mock_get_responses(self.DEFAULT_EXPECT, 404, 200):
 523             self.check_exception(arvados.errors.NotFoundError, num_retries=3)
 524
 525     def test_general_exception_with_mixed_errors(self):
 526         # get should raise a NotFoundError if no server returns the block,
 527         # and a high threshold of servers report that it's not found.
 528         # This test rigs up 50/50 disagreement between two servers, and
 529         # checks that it does not become a NotFoundError.
 530         client = self.new_client()
 531         with tutil.mock_get_responses(self.DEFAULT_EXPECT, 404, 500):
 532             with self.assertRaises(arvados.errors.KeepReadError) as exc_check:
 533                 client.get(self.HINTED_LOCATOR)
 534             self.assertNotIsInstance(
 535                 exc_check.exception, arvados.errors.NotFoundError,
 536                 "mixed errors raised NotFoundError")
 537
 538     def test_hint_server_can_succeed_without_retries(self):
 539         with tutil.mock_get_responses(self.DEFAULT_EXPECT, 404, 200, 500):
 540             self.check_success(locator=self.HINTED_LOCATOR)
 541
 542     def test_try_next_server_after_timeout(self):
 543         side_effects = [
 544             socket.timeout("timed out"),
 545             tutil.fake_requests_response(200, self.DEFAULT_EXPECT)]
 546         with mock.patch('requests.get',
 547                         side_effect=iter(side_effects)):
 548             self.check_success(locator=self.HINTED_LOCATOR)
 549
 550     def test_retry_data_with_wrong_checksum(self):
 551         side_effects = (tutil.fake_requests_response(200, s)
 552                         for s in ['baddata', self.TEST_DATA])
 553         with mock.patch('requests.get', side_effect=side_effects):
 554             self.check_success(locator=self.HINTED_LOCATOR)
 555
 556
 557 @tutil.skip_sleep
 558 class KeepClientRetryPutTestCase(KeepClientRetryTestMixin, unittest.TestCase):
 559     DEFAULT_EXPECT = KeepClientRetryTestMixin.TEST_LOCATOR
 560     DEFAULT_EXCEPTION = arvados.errors.KeepWriteError
 561     TEST_PATCHER = staticmethod(tutil.mock_put_responses)
 562
 563     def run_method(self, data=KeepClientRetryTestMixin.TEST_DATA,
 564                    copies=1, *args, **kwargs):
 565         return self.new_client().put(data, copies, *args, **kwargs)
 566
 567     def test_do_not_send_multiple_copies_to_same_server(self):
 568         with tutil.mock_put_responses(self.DEFAULT_EXPECT, 200):
 569             self.check_exception(copies=2, num_retries=3)