Add retry_with_timeout() utility function

bin/tests/system/isctest/__init__.py

@@ -13,6 +13,7 @@ from . import check
 from . import instance
 from . import query
 from . import rndc
+from . import run
 from . import log
 
 # isctest.mark module is intentionally NOT imported, because it relies on

bin/tests/system/isctest/run.py

@@ -0,0 +1,23 @@
+# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+#
+# SPDX-License-Identifier: MPL-2.0
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0.  If a copy of the MPL was not distributed with this
+# file, you can obtain one at https://mozilla.org/MPL/2.0/.
+#
+# See the COPYRIGHT file distributed with this work for additional
+# information regarding copyright ownership.
+
+import time
+
+
+def retry_with_timeout(func, timeout, delay=1, msg=None):
+    start_time = time.time()
+    while time.time() < start_time + timeout:
+        if func():
+            return
+        time.sleep(delay)
+    if msg is None:
+        msg = f"{func.__module__}.{func.__qualname__} timed out after {timeout} s"
+    assert False, msg