tests: save/restore SCYLLA_EXT_OPTS to prevent env variable leak

Several test modules set SCYLLA_EXT_OPTS in setup_module() but never
restore it in teardown_module(). When tests are reordered to share
clusters, stale values can leak into subsequent modules and cause
misconfigured clusters.

Save the original value before overwriting and restore it on
teardown in:
- test_cluster.py
- test_shard_aware.py
- test_use_keyspace.py
- test_ip_change.py
- test_client_routes.py (module-level and TestFullNodeReplacementThroughNlb)
- test_authentication.py

Author: mykaul

tests/integration/standard/test_authentication.py

@@ -34,8 +34,12 @@
 #This can be tested for remote hosts, but the cluster has to be configured accordingly
 #@local
 
+_saved_scylla_ext_opts = None
+
 
 def setup_module():
+    global _saved_scylla_ext_opts
+    _saved_scylla_ext_opts = os.environ.get('SCYLLA_EXT_OPTS')
     if CASSANDRA_IP.startswith("127.0.0.") and not USE_CASS_EXTERNAL:
         use_singledc(start=False)
         ccm_cluster = get_cluster()
@@ -71,6 +75,10 @@ def _check_auth_ready():
 
 def teardown_module():
     remove_cluster()  # this test messes with config
+    if _saved_scylla_ext_opts is None:
+        os.environ.pop('SCYLLA_EXT_OPTS', None)
+    else:
+        os.environ['SCYLLA_EXT_OPTS'] = _saved_scylla_ext_opts
 
 
 class AuthenticationTests(unittest.TestCase):

tests/integration/standard/test_client_routes.py

@@ -519,10 +519,22 @@ def assert_routes_direct(test, cluster, expected_node_ids, direct_port=9042):
         )
 
 
+_saved_scylla_ext_opts = None
+
+
 def setup_module():
+    global _saved_scylla_ext_opts
+    _saved_scylla_ext_opts = os.environ.get('SCYLLA_EXT_OPTS')
     os.environ['SCYLLA_EXT_OPTS'] = "--smp 2 --memory 2048M"
     use_cluster('shared_aware', [3], start=True)
 
+
+def teardown_module():
+    if _saved_scylla_ext_opts is None:
+        os.environ.pop('SCYLLA_EXT_OPTS', None)
+    else:
+        os.environ['SCYLLA_EXT_OPTS'] = _saved_scylla_ext_opts
+
 @skip_scylla_version_lt(reason='scylladb/scylladb#26992 - system.client_routes is not yet supported',
                         scylla_version="2026.1.0")
 class TestGetHostPortMapping(unittest.TestCase):
@@ -1116,6 +1128,7 @@ class TestFullNodeReplacementThroughNlb(unittest.TestCase):
 
     @classmethod
     def setUpClass(cls):
+        cls._saved_scylla_ext_opts = os.environ.get('SCYLLA_EXT_OPTS')
         os.environ['SCYLLA_EXT_OPTS'] = "--smp 2 --memory 2048M"
         use_cluster('test_client_routes_replacement', [3], start=True)
 
@@ -1133,6 +1146,10 @@ def setUpClass(cls):
     @classmethod
     def tearDownClass(cls):
         cls.direct_cluster.shutdown()
+        if cls._saved_scylla_ext_opts is None:
+            os.environ.pop('SCYLLA_EXT_OPTS', None)
+        else:
+            os.environ['SCYLLA_EXT_OPTS'] = cls._saved_scylla_ext_opts
 
     def test_should_survive_full_node_replacement_through_nlb(self):
         """

tests/integration/standard/test_cluster.py

@@ -51,12 +51,24 @@
 log = logging.getLogger(__name__)
 
 
+_saved_scylla_ext_opts = None
+
+
 def setup_module():
+    global _saved_scylla_ext_opts
+    _saved_scylla_ext_opts = os.environ.get('SCYLLA_EXT_OPTS')
     os.environ['SCYLLA_EXT_OPTS'] = "--smp 2"
     use_cluster("cluster_tests", [3], start=True, workloads=None)
     warnings.simplefilter("always")
 
 
+def teardown_module():
+    if _saved_scylla_ext_opts is None:
+        os.environ.pop('SCYLLA_EXT_OPTS', None)
+    else:
+        os.environ['SCYLLA_EXT_OPTS'] = _saved_scylla_ext_opts
+
+
 class IgnoredHostPolicy(RoundRobinPolicy):
 
     def __init__(self, ignored_hosts):

tests/integration/standard/test_ip_change.py

@@ -10,11 +10,22 @@
 
 LOGGER = logging.getLogger(__name__)
 
+_saved_scylla_ext_opts = None
+
 
 def setup_module():
+    global _saved_scylla_ext_opts
+    _saved_scylla_ext_opts = os.environ.get('SCYLLA_EXT_OPTS')
     os.environ['SCYLLA_EXT_OPTS'] = "--smp 2 --memory 2048M"
     use_cluster('test_ip_change', [3], start=True)
 
+
+def teardown_module():
+    if _saved_scylla_ext_opts is None:
+        os.environ.pop('SCYLLA_EXT_OPTS', None)
+    else:
+        os.environ['SCYLLA_EXT_OPTS'] = _saved_scylla_ext_opts
+
 @local
 class TestIpAddressChange(unittest.TestCase):
     @classmethod

tests/integration/standard/test_shard_aware.py

@@ -31,11 +31,23 @@
 LOGGER = logging.getLogger(__name__)
 
 
+_saved_scylla_ext_opts = None
+
+
 def setup_module():
+    global _saved_scylla_ext_opts
+    _saved_scylla_ext_opts = os.environ.get('SCYLLA_EXT_OPTS')
     os.environ['SCYLLA_EXT_OPTS'] = "--smp 2"
     use_cluster('cluster_tests', [3], start=True)
 
 
+def teardown_module():
+    if _saved_scylla_ext_opts is None:
+        os.environ.pop('SCYLLA_EXT_OPTS', None)
+    else:
+        os.environ['SCYLLA_EXT_OPTS'] = _saved_scylla_ext_opts
+
+
 class TestShardAwareIntegration(unittest.TestCase):
     @classmethod
     def setup_class(cls):

tests/integration/standard/test_use_keyspace.py

@@ -14,12 +14,23 @@
 
 LOGGER = logging.getLogger(__name__)
 
+_saved_scylla_ext_opts = None
+
 
 def setup_module():
+    global _saved_scylla_ext_opts
+    _saved_scylla_ext_opts = os.environ.get('SCYLLA_EXT_OPTS')
     os.environ['SCYLLA_EXT_OPTS'] = "--smp 2 --memory 2048M"
     use_cluster('shared_aware', [3], start=True)
 
 
+def teardown_module():
+    if _saved_scylla_ext_opts is None:
+        os.environ.pop('SCYLLA_EXT_OPTS', None)
+    else:
+        os.environ['SCYLLA_EXT_OPTS'] = _saved_scylla_ext_opts
+
+
 @local
 class TestUseKeyspace(unittest.TestCase):
     @classmethod