test: try mitigating port clashes

Also, I don't think calling random.seed is necessary.

2 files changed, 25 insertions, 9 deletions

diff --git a/test/py/conftest.py b/test/py/conftest.py
index 355bd83..9551210 100644
--- a/test/py/conftest.py
+++ b/test/py/conftest.py
@@ -5,10 +5,10 @@
 
 import logging
 import os
-import random
 
 from pytest import fixture
 
+from lib.net import random_unused_port
 from lib.process import CmdLine
 from lib.test_repo import TestRepo
 
@@ -75,11 +75,6 @@ def pytest_generate_tests(metafunc):
             metafunc.parametrize(opt.codename, metafunc.config.getoption(opt.codename))
 
 
-@fixture(scope='session')
-def rng():
-    random.seed()
-
-
 class Paths:
     def __init__(self, pytestconfig):
         for opt in BINARY_PARAMS:
@@ -113,9 +108,9 @@ def version(pytestconfig):
     return pytestconfig.getoption(PARAM_VERSION.codename)
 
 
-@fixture
-def server_port(rng):
-    return str(random.randint(2000, 50000))
+@fixture(scope='session')
+def server_port():
+    return str(random_unused_port())
 
 
 @fixture
diff --git a/test/py/lib/net.py b/test/py/lib/net.py
new file mode 100644
index 0000000..816dd99
--- /dev/null
+++ b/test/py/lib/net.py
@@ -0,0 +1,21 @@
+# Copyright (c) 2023 Egor Tensin <Egor.Tensin@gmail.com>
+# This file is part of the "cimple" project.
+# For details, see https://github.com/egor-tensin/cimple.
+# Distributed under the MIT License.
+
+from contextlib import closing
+import random
+import socket
+
+
+def port_is_open(host, port):
+    with closing(socket.socket(socket.AF_INET, socket.SOCK_STREAM)) as sock:
+        return sock.connect_ex((host, port)) == 0
+
+
+def random_unused_port():
+    while True:
+        port = random.randint(20000, 40000)
+        if port_is_open('127.0.0.1', port):
+            continue
+        return port