test: check default value of tombstone_gc

Add a test which checks whether default tombstone_gc value is properly
set and if it does not override previous setting.

test/topology_experimental_raft/test_tombstone_gc.py

@@ -0,0 +1,39 @@
+#
+# Copyright (C) 2024-present ScyllaDB
+#
+# SPDX-License-Identifier: AGPL-3.0-or-later
+#
+import logging
+import pytest
+
+from test.topology.util import new_test_keyspace, new_test_table
+
+logger = logging.getLogger(__name__)
+
+def check_tombstone_gc_mode(cql, table, mode):
+    s = list(cql.execute(f"DESC {table}"))[0].create_statement
+    assert f"'mode': '{mode}'" in s
+
+def get_expected_tombstone_gc_mode(rf, tablets):
+    return "repair" if tablets and rf > 1 else "timeout"
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize("rf", [1, 2])
+@pytest.mark.parametrize("tablets", ["true", "false"])
+async def test_default_tombstone_gc(manager, rf, tablets):
+    servers = [await manager.server_add(), await manager.server_add()]
+    cql = manager.cql
+    async with new_test_keyspace(cql, f"with replication = {{ 'class': 'NetworkTopologyStrategy', 'replication_factor': {rf}}} and tablets = {{'initial': {rf}}}") as keyspace:
+        async with new_test_table(cql, keyspace, "p int primary key, x int") as table:
+            check_tombstone_gc_mode(cql, table, get_expected_tombstone_gc_mode(rf, tablets))
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize("rf", [1, 2])
+@pytest.mark.parametrize("tablets", ["true", "false"])
+async def test_default_tombstone_gc_does_not_override(manager, rf, tablets):
+    servers = [await manager.server_add(), await manager.server_add()]
+    cql = manager.cql
+    async with new_test_keyspace(cql, f"with replication = {{ 'class': 'NetworkTopologyStrategy', 'replication_factor': {rf}}} and tablets = {{'initial': {rf}}}") as keyspace:
+        async with new_test_table(cql, keyspace, "p int primary key, x int", " with tombstone_gc = {'mode': 'disabled'}") as table:
+            await cql.run_async(f"ALTER TABLE {table} add y int")
+            check_tombstone_gc_mode(cql, table, "disabled")