add integ tests for new setting

tests/integration/test_max_authentication_methods_per_user/configs/max_auth_limited.xml

@@ -0,0 +1,3 @@
+<clickhouse>
+    <max_authentication_methods_per_user>2</max_authentication_methods_per_user>
+</clickhouse>

tests/integration/test_max_authentication_methods_per_user/test.py

@@ -0,0 +1,49 @@
+import pytest
+from helpers.cluster import ClickHouseCluster
+from helpers.client import QueryRuntimeException
+
+cluster = ClickHouseCluster(__file__)
+
+limited_node = cluster.add_instance(
+    "limited_node",
+    main_configs=["configs/max_auth_limited.xml"],
+)
+
+default_node = cluster.add_instance(
+    "default_node",
+)
+
+
+@pytest.fixture(scope="module")
+def started_cluster():
+    try:
+        cluster.start()
+        yield cluster
+
+    finally:
+        cluster.shutdown()
+
+
+def test_create(started_cluster):
+    expected_error = "User can not be created/updated because it exceeds the allowed quantity of authentication methods per user"
+    assert expected_error in limited_node.query_and_get_error("CREATE USER u_max_authentication_methods IDENTIFIED BY '1', BY '2', BY '3'")
+
+
+    assert expected_error not in limited_node.query_and_get_answer_with_error("CREATE USER u_max_authentication_methods IDENTIFIED BY '1', BY '2'")
+
+    limited_node.query("DROP USER u_max_authentication_methods")
+
+def test_alter(started_cluster):
+    limited_node.query("CREATE USER u_max_authentication_methods IDENTIFIED BY '1'")
+
+    expected_error = "User can not be created/updated because it exceeds the allowed quantity of authentication methods per user"
+    assert expected_error in limited_node.query_and_get_error("ALTER USER u_max_authentication_methods ADD IDENTIFIED BY '2', BY '3'")
+
+    expected_error = "User can not be created/updated because it exceeds the allowed quantity of authentication methods per user"
+    assert expected_error in limited_node.query_and_get_error("ALTER USER u_max_authentication_methods IDENTIFIED BY '3', BY '4', BY '5'")
+
+    assert expected_error not in limited_node.query_and_get_answer_with_error("ALTER USER u_max_authentication_methods ADD IDENTIFIED BY '2'")
+
+    assert expected_error not in limited_node.query_and_get_answer_with_error("ALTER USER u_max_authentication_methods IDENTIFIED BY '2', BY '3'")
+
+    limited_node.query("DROP USER u_max_authentication_methods")