text: import pytest
  
  from helpers.cluster import ClickHouseCluster
  
  cluster = ClickHouseCluster(__file__)
  node1 = cluster.add_instance('node1', user_configs=['configs/config_no_substs.xml'])  # hardcoded value 33333
  node2 = cluster.add_instance('node2', user_configs=['configs/config_env.xml'],
                               env_variables={"MAX_QUERY_SIZE": "55555"})
  node3 = cluster.add_instance('node3', user_configs=['configs/config_zk.xml'], with_zookeeper=True)
  node4 = cluster.add_instance('node4', user_configs=['configs/config_incl.xml'],
                               main_configs=['configs/max_query_size.xml'])  # include value 77777
  node5 = cluster.add_instance('node5', user_configs=['configs/config_allow_databases.xml'])
  node6 = cluster.add_instance('node6', user_configs=['configs/config_include_from_env.xml'],
                               env_variables={"INCLUDE_FROM_ENV": "/etc/clickhouse-server/config.d/max_query_size.xml"},
                               main_configs=['configs/max_query_size.xml'])
  
  
  @pytest.fixture(scope="module")
  def start_cluster():
      try:
          def create_zk_roots(zk):
              zk.create(path="/setting/max_query_size", value=b"77777", makepath=True)
  
          cluster.add_zookeeper_startup_command(create_zk_roots)
  
          cluster.start()
          yield cluster
      finally:
          cluster.shutdown()
  
  
  def test_config(start_cluster):
      assert node1.query("select value from system.settings where name = 'max_query_size'") == "33333\n"
      assert node2.query("select value from system.settings where name = 'max_query_size'") == "55555\n"
      assert node3.query("select value from system.settings where name = 'max_query_size'") == "77777\n"
      assert node4.query("select value from system.settings where name = 'max_query_size'") == "99999\n"
      assert node6.query("select value from system.settings where name = 'max_query_size'") == "99999\n"
  
  
  def test_allow_databases(start_cluster):
      node5.query("CREATE DATABASE db1")
      node5.query(
          "CREATE TABLE db1.test_table(date Date, k1 String, v1 Int32) ENGINE = MergeTree(date, (k1, date), 8192)")
      node5.query("INSERT INTO db1.test_table VALUES('2000-01-01', 'test_key', 1)")
      assert node5.query("SELECT name FROM system.databases WHERE name = 'db1'") == "db1\n"
      assert node5.query(
          "SELECT name FROM system.tables WHERE database = 'db1' AND name = 'test_table' ") == "test_table\n"
      assert node5.query(
          "SELECT name FROM system.columns WHERE database = 'db1' AND table = 'test_table'") == "date\nk1\nv1\n"
      assert node5.query(
          "SELECT name FROM system.parts WHERE database = 'db1' AND table = 'test_table'") == "20000101_20000101_1_1_0\n"
      assert node5.query(
          "SELECT name FROM system.parts_columns WHERE database = 'db1' AND table = 'test_table'") == "20000101_20000101_1_1_0\n20000101_20000101_1_1_0\n20000101_20000101_1_1_0\n"
  
      assert node5.query("SELECT name FROM system.databases WHERE name = 'db1'", user="test_allow").strip() == ""
      assert node5.query("SELECT name FROM system.tables WHERE database = 'db1' AND name = 'test_table'",
                         user="test_allow").strip() == ""
      assert node5.query("SELECT name FROM system.columns WHERE database = 'db1' AND table = 'test_table'",
                         user="test_allow").strip() == ""
      assert node5.query("SELECT name FROM system.parts WHERE database = 'db1' AND table = 'test_table'",
                         user="test_allow").strip() == ""
      assert node5.query("SELECT name FROM system.parts_columns WHERE database = 'db1' AND table = 'test_table'",
                         user="test_allow").strip() == ""
  