Add integration test

Signed-off-by: JaySon-Huang <tshent@qq.com>

tests/integration/test_cgroup_limit/test.py

@@ -0,0 +1,37 @@
+#!/usr/bin/env python3
+
+import os
+import math
+import subprocess
+from tempfile import NamedTemporaryFile
+import pytest
+
+def run_command_in_container(cmd, *args):
+    # /clickhouse is mounted by interation tests runner
+    alternative_binary = os.getenv('CLICKHOUSE_BINARY', '/clickhouse')
+    if alternative_binary:
+        args += (
+            '--volume', f'{alternative_binary}:/usr/bin/clickhouse',
+        )
+
+    return subprocess.check_output(['docker', 'run', '--rm',
+        *args,
+        'ubuntu:20.04',
+        'sh', '-c', cmd,
+    ])
+
+def run_with_cpu_limit(cmd, num_cpus, *args):
+    args += (
+        '--cpus', f'{num_cpus}',
+    )
+    return run_command_in_container(cmd, *args)
+
+def test_cgroup_cpu_limit():
+    for num_cpus in (1, 2, 4, 2.8):
+        result = run_with_cpu_limit('clickhouse local -q "select value from system.settings where name=\'max_threads\'"', num_cpus)
+        expect_output = (r"\'auto({})\'".format(math.ceil(num_cpus))).encode()
+        assert result.strip() == expect_output, f"fail for cpu limit={num_cpus}, result={result.strip()}, expect={expect_output}"
+
+# For manual run
+if __name__ == '__main__':
+    test_cgroup_cpu_limit()