Get rid of contextlib.nested() for py3

contextlib.nested() is missing completely in Python 3.

Since 2.7, we can use multiple context managers in a 'with' statement,
like so:

    with thing1() as t1, thing2() as t2:
        do_stuff()

Now, if we had some code that needed to nest an arbitrary number of
context managers, there's stuff we could do with contextlib.ExitStack
and such... but we don't. We only use contextlib.nested() in tests to
set up bunches of mocks without crazy-deep indentation, and all that
stuff fits perfectly into multiple-context-manager 'with' statements.

Change-Id: Id472958b007948f05dbd4c7fb8cf3ffab58e2681

test/unit/account/test_reaper.py

@@ -22,7 +22,6 @@
 
 from logging import DEBUG
 from mock import patch, call, DEFAULT
-from contextlib import nested
 import six
 
 from swift.account import reaper
@@ -415,15 +414,14 @@ def test_reap_container_get_object_fail(self):
         self.reap_obj_fail = False
         self.amount_delete_fail = 0
         self.max_delete_fail = 0
-        ctx = [patch('swift.account.reaper.direct_get_container',
-                     self.fake_direct_get_container),
-               patch('swift.account.reaper.direct_delete_container',
-                     self.fake_direct_delete_container),
-               patch('swift.account.reaper.AccountReaper.get_container_ring',
-                     self.fake_container_ring),
-               patch('swift.account.reaper.AccountReaper.reap_object',
-                     self.fake_reap_object)]
-        with nested(*ctx):
+        with patch('swift.account.reaper.direct_get_container',
+                   self.fake_direct_get_container), \
+                patch('swift.account.reaper.direct_delete_container',
+                      self.fake_direct_delete_container), \
+                patch('swift.account.reaper.AccountReaper.get_container_ring',
+                      self.fake_container_ring), \
+                patch('swift.account.reaper.AccountReaper.reap_object',
+                      self.fake_reap_object):
             r.reap_container('a', 'partition', acc_nodes, 'c')
         self.assertEqual(r.logger.get_increment_counts()['return_codes.4'], 1)
         self.assertEqual(r.stats_containers_deleted, 1)
@@ -434,15 +432,14 @@ def test_reap_container_partial_fail(self):
         self.reap_obj_fail = False
         self.amount_delete_fail = 0
         self.max_delete_fail = 2
-        ctx = [patch('swift.account.reaper.direct_get_container',
-                     self.fake_direct_get_container),
-               patch('swift.account.reaper.direct_delete_container',
-                     self.fake_direct_delete_container),
-               patch('swift.account.reaper.AccountReaper.get_container_ring',
-                     self.fake_container_ring),
-               patch('swift.account.reaper.AccountReaper.reap_object',
-                     self.fake_reap_object)]
-        with nested(*ctx):
+        with patch('swift.account.reaper.direct_get_container',
+                   self.fake_direct_get_container), \
+                patch('swift.account.reaper.direct_delete_container',
+                      self.fake_direct_delete_container), \
+                patch('swift.account.reaper.AccountReaper.get_container_ring',
+                      self.fake_container_ring), \
+                patch('swift.account.reaper.AccountReaper.reap_object',
+                      self.fake_reap_object):
             r.reap_container('a', 'partition', acc_nodes, 'c')
         self.assertEqual(r.logger.get_increment_counts()['return_codes.4'], 2)
         self.assertEqual(r.stats_containers_possibly_remaining, 1)
@@ -453,15 +450,14 @@ def test_reap_container_full_fail(self):
         self.reap_obj_fail = False
         self.amount_delete_fail = 0
         self.max_delete_fail = 3
-        ctx = [patch('swift.account.reaper.direct_get_container',
-                     self.fake_direct_get_container),
-               patch('swift.account.reaper.direct_delete_container',
-                     self.fake_direct_delete_container),
-               patch('swift.account.reaper.AccountReaper.get_container_ring',
-                     self.fake_container_ring),
-               patch('swift.account.reaper.AccountReaper.reap_object',
-                     self.fake_reap_object)]
-        with nested(*ctx):
+        with patch('swift.account.reaper.direct_get_container',
+                   self.fake_direct_get_container), \
+                patch('swift.account.reaper.direct_delete_container',
+                      self.fake_direct_delete_container), \
+                patch('swift.account.reaper.AccountReaper.get_container_ring',
+                      self.fake_container_ring), \
+                patch('swift.account.reaper.AccountReaper.reap_object',
+                      self.fake_reap_object):
             r.reap_container('a', 'partition', acc_nodes, 'c')
         self.assertEqual(r.logger.get_increment_counts()['return_codes.4'], 3)
         self.assertEqual(r.stats_containers_remaining, 1)
@@ -532,11 +528,10 @@ def test_reap_account_no_container(self):
         self.r = r = self.init_reaper({}, fakelogger=True)
         self.called_amount = 0
         r.start_time = time.time()
-        ctx = [patch('swift.account.reaper.AccountReaper.reap_container',
-                     self.fake_reap_container),
-               patch('swift.account.reaper.AccountReaper.get_account_ring',
-                     self.fake_account_ring)]
-        with nested(*ctx):
+        with patch('swift.account.reaper.AccountReaper.reap_container',
+                   self.fake_reap_container), \
+                patch('swift.account.reaper.AccountReaper.get_account_ring',
+                      self.fake_account_ring):
             nodes = r.get_account_ring().get_part_nodes()
             self.assertTrue(r.reap_account(broker, 'partition', nodes))
         self.assertTrue(r.logger.get_lines_for_level(
@@ -548,13 +543,12 @@ def test_reap_device(self):
         self.called_amount = 0
         conf = {'devices': devices}
         r = self.init_reaper(conf)
-        ctx = [patch('swift.account.reaper.AccountBroker',
-                     FakeAccountBroker),
-               patch('swift.account.reaper.AccountReaper.get_account_ring',
-                     self.fake_account_ring),
-               patch('swift.account.reaper.AccountReaper.reap_account',
-                     self.fake_reap_account)]
-        with nested(*ctx):
+        with patch('swift.account.reaper.AccountBroker',
+                   FakeAccountBroker), \
+                patch('swift.account.reaper.AccountReaper.get_account_ring',
+                      self.fake_account_ring), \
+                patch('swift.account.reaper.AccountReaper.reap_account',
+                      self.fake_reap_account):
             r.reap_device('sda1')
         self.assertEqual(self.called_amount, 1)
 
@@ -563,13 +557,12 @@ def test_reap_device_with_ts(self):
         self.called_amount = 0
         conf = {'devices': devices}
         r = self.init_reaper(conf=conf)
-        ctx = [patch('swift.account.reaper.AccountBroker',
-                     FakeAccountBroker),
-               patch('swift.account.reaper.AccountReaper.get_account_ring',
-                     self.fake_account_ring),
-               patch('swift.account.reaper.AccountReaper.reap_account',
-                     self.fake_reap_account)]
-        with nested(*ctx):
+        with patch('swift.account.reaper.AccountBroker',
+                   FakeAccountBroker), \
+                patch('swift.account.reaper.AccountReaper.get_account_ring',
+                      self.fake_account_ring), \
+                patch('swift.account.reaper.AccountReaper.reap_account',
+                      self.fake_reap_account):
             r.reap_device('sda1')
         self.assertEqual(self.called_amount, 0)
 
@@ -578,13 +571,12 @@ def test_reap_device_with_not_my_ip(self):
         self.called_amount = 0
         conf = {'devices': devices}
         r = self.init_reaper(conf, myips=['10.10.1.2'])
-        ctx = [patch('swift.account.reaper.AccountBroker',
-                     FakeAccountBroker),
-               patch('swift.account.reaper.AccountReaper.get_account_ring',
-                     self.fake_account_ring),
-               patch('swift.account.reaper.AccountReaper.reap_account',
-                     self.fake_reap_account)]
-        with nested(*ctx):
+        with patch('swift.account.reaper.AccountBroker',
+                   FakeAccountBroker), \
+                patch('swift.account.reaper.AccountReaper.get_account_ring',
+                      self.fake_account_ring), \
+                patch('swift.account.reaper.AccountReaper.reap_account',
+                      self.fake_reap_account):
             r.reap_device('sda1')
         self.assertEqual(self.called_amount, 0)
 
@@ -627,14 +619,14 @@ def fake_reap_container(self, account, account_partition,
                                 account_nodes, container):
             container_reaped[0] += 1
 
-        ctx = [patch('swift.account.reaper.AccountBroker',
-                     FakeAccountBroker),
-               patch('swift.account.reaper.AccountBroker.list_containers_iter',
-                     fake_list_containers_iter),
-               patch('swift.account.reaper.AccountReaper.reap_container',
-                     fake_reap_container), ]
         fake_ring = FakeRing()
-        with nested(*ctx):
+        with patch('swift.account.reaper.AccountBroker',
+                   FakeAccountBroker), \
+                patch(
+                    'swift.account.reaper.AccountBroker.list_containers_iter',
+                    fake_list_containers_iter), \
+                patch('swift.account.reaper.AccountReaper.reap_container',
+                      fake_reap_container):
             fake_broker = FakeAccountBroker(['c', 'd', 'e'])
             r.reap_account(fake_broker, 10, fake_ring.nodes, 0)
             self.assertEqual(container_reaped[0], 1)

test/unit/cli/test_recon.py

@@ -13,7 +13,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from contextlib import nested
 import json
 import mock
 import os
@@ -240,11 +239,8 @@ def test_get_ringmd5(self):
             mock_scout.return_value = scout_instance
             stdout = StringIO()
             mock_hash = mock.MagicMock()
-            patches = [
-                mock.patch('sys.stdout', new=stdout),
-                mock.patch('swift.cli.recon.md5', new=mock_hash),
-            ]
-            with nested(*patches):
+            with mock.patch('sys.stdout', new=stdout), \
+                    mock.patch('swift.cli.recon.md5', new=mock_hash):
                 mock_hash.return_value.hexdigest.return_value = \
                     empty_file_hash
                 self.recon_instance.get_ringmd5(hosts, self.swift_dir)
@@ -295,11 +291,9 @@ def mock_scout_quarantine(app, host):
             return url, response, status, 0, 0
 
         stdout = StringIO()
-        patches = [
-            mock.patch('swift.cli.recon.Scout.scout', mock_scout_quarantine),
-            mock.patch('sys.stdout', new=stdout),
-        ]
-        with nested(*patches):
+        with mock.patch('swift.cli.recon.Scout.scout',
+                        mock_scout_quarantine), \
+                mock.patch('sys.stdout', new=stdout):
             self.recon_instance.quarantine_check(hosts)
 
         output = stdout.getvalue()
@@ -332,11 +326,9 @@ def mock_scout_driveaudit(app, host):
             return url, response, status, 0, 0
 
         stdout = StringIO()
-        patches = [
-            mock.patch('swift.cli.recon.Scout.scout', mock_scout_driveaudit),
-            mock.patch('sys.stdout', new=stdout),
-        ]
-        with nested(*patches):
+        with mock.patch('swift.cli.recon.Scout.scout',
+                        mock_scout_driveaudit), \
+                mock.patch('sys.stdout', new=stdout):
             self.recon_instance.driveaudit_check(hosts)
 
         output = stdout.getvalue()
@@ -394,19 +386,15 @@ def mock_scout_server_type(app, host):
             return url, response, status
 
         stdout = StringIO()
-        patches = [
-            mock.patch('swift.cli.recon.Scout.scout_server_type',
-                       mock_scout_server_type),
-            mock.patch('sys.stdout', new=stdout),
-        ]
-
         res_object = 'Invalid: http://127.0.0.1:6010/ is object-server'
         res_container = 'Invalid: http://127.0.0.1:6011/ is container-server'
         res_account = 'Invalid: http://127.0.0.1:6012/ is account-server'
         valid = "1/1 hosts ok, 0 error[s] while checking hosts."
 
         # Test for object server type - default
-        with nested(*patches):
+        with mock.patch('swift.cli.recon.Scout.scout_server_type',
+                        mock_scout_server_type), \
+                mock.patch('sys.stdout', new=stdout):
             self.recon.server_type_check(hosts)
 
         output = stdout.getvalue()
@@ -415,15 +403,19 @@ def mock_scout_server_type(app, host):
         stdout.truncate(0)
 
         # Test ok for object server type - default
-        with nested(*patches):
+        with mock.patch('swift.cli.recon.Scout.scout_server_type',
+                        mock_scout_server_type), \
+                mock.patch('sys.stdout', new=stdout):
             self.recon.server_type_check([hosts[0]])
 
         output = stdout.getvalue()
         self.assertTrue(valid in output.splitlines())
         stdout.truncate(0)
 
         # Test for account server type
-        with nested(*patches):
+        with mock.patch('swift.cli.recon.Scout.scout_server_type',
+                        mock_scout_server_type), \
+                mock.patch('sys.stdout', new=stdout):
             self.recon.server_type = 'account'
             self.recon.server_type_check(hosts)
 
@@ -433,7 +425,9 @@ def mock_scout_server_type(app, host):
         stdout.truncate(0)
 
         # Test ok for account server type
-        with nested(*patches):
+        with mock.patch('swift.cli.recon.Scout.scout_server_type',
+                        mock_scout_server_type), \
+                mock.patch('sys.stdout', new=stdout):
             self.recon.server_type = 'account'
             self.recon.server_type_check([hosts[2]])
 
@@ -442,7 +436,9 @@ def mock_scout_server_type(app, host):
         stdout.truncate(0)
 
         # Test for container server type
-        with nested(*patches):
+        with mock.patch('swift.cli.recon.Scout.scout_server_type',
+                        mock_scout_server_type), \
+                mock.patch('sys.stdout', new=stdout):
             self.recon.server_type = 'container'
             self.recon.server_type_check(hosts)
 
@@ -452,7 +448,9 @@ def mock_scout_server_type(app, host):
         stdout.truncate(0)
 
         # Test ok for container server type
-        with nested(*patches):
+        with mock.patch('swift.cli.recon.Scout.scout_server_type',
+                        mock_scout_server_type), \
+                mock.patch('sys.stdout', new=stdout):
             self.recon.server_type = 'container'
             self.recon.server_type_check([hosts[1]])
 

test/unit/common/middleware/test_dlo.py

@@ -14,7 +14,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import contextlib
 import hashlib
 import json
 import mock
@@ -701,12 +700,11 @@ def mock_is_success(status_int):
             '/v1/AUTH_test/mancon/manifest',
             environ={'REQUEST_METHOD': 'GET'})
 
-        with contextlib.nested(
-                mock.patch('swift.common.request_helpers.time.time',
-                           mock_time),
+        with mock.patch('swift.common.request_helpers.time.time',
+                        mock_time), \
                 mock.patch('swift.common.request_helpers.is_success',
-                           mock_is_success),
-                mock.patch.object(dlo, 'is_success', mock_is_success)):
+                           mock_is_success), \
+                mock.patch.object(dlo, 'is_success', mock_is_success):
             status, headers, body, exc = self.call_dlo(
                 req, expect_exception=True)
 

test/unit/common/middleware/test_slo.py

@@ -19,7 +19,6 @@
 import hashlib
 import time
 import unittest
-from contextlib import nested
 from mock import patch
 from hashlib import md5
 from swift.common import swob, utils
@@ -2250,13 +2249,13 @@ def mock_is_success(status_int):
             '/v1/AUTH_test/gettest/manifest-abcd',
             environ={'REQUEST_METHOD': 'GET'})
 
-        with nested(patch.object(slo, 'is_success', mock_is_success),
-                    patch('swift.common.request_helpers.time.time',
-                          mock_time),
-                    patch('swift.common.request_helpers.is_success',
-                          mock_is_success)):
-                status, headers, body, exc = self.call_slo(
-                    req, expect_exception=True)
+        with patch.object(slo, 'is_success', mock_is_success), \
+                patch('swift.common.request_helpers.time.time',
+                      mock_time), \
+                patch('swift.common.request_helpers.is_success',
+                      mock_is_success):
+            status, headers, body, exc = self.call_slo(
+                req, expect_exception=True)
 
         self.assertIsInstance(exc, SegmentError)
         self.assertEqual(status, '200 OK')

test/unit/common/middleware/test_tempauth.py

@@ -16,7 +16,7 @@
 
 import json
 import unittest
-from contextlib import contextmanager, nested
+from contextlib import contextmanager
 from base64 import b64encode
 from time import time
 import mock
@@ -273,8 +273,8 @@ def test_auth_with_s3_authorization(self):
                                  headers={'X-Auth-Token': 't',
                                           'AUTHORIZATION': 'AWS s3:s3:pass'})
 
-        with nested(mock.patch('base64.urlsafe_b64decode'),
-                    mock.patch('base64.encodestring')) as (msg, sign):
+        with mock.patch('base64.urlsafe_b64decode') as msg, \
+                mock.patch('base64.encodestring') as sign:
             msg.return_value = ''
             sign.return_value = 'pass'
             resp = req.get_response(local_auth)