diff --git a/bin/tests/system/conftest.py b/bin/tests/system/conftest.py
index ac14893a2b..9a741b1cc8 100644
--- a/bin/tests/system/conftest.py
+++ b/bin/tests/system/conftest.py
@@ -23,6 +23,9 @@ from typing import Any, Dict, List, Optional
 import pytest
 
 
+pytest.register_assert_rewrite("isctest")
+
+
 # Silence warnings caused by passing a pytest fixture to another fixture.
 # pylint: disable=redefined-outer-name
 
diff --git a/bin/tests/system/isctest/__init__.py b/bin/tests/system/isctest/__init__.py
new file mode 100644
index 0000000000..0f2eae1fb1
--- /dev/null
+++ b/bin/tests/system/isctest/__init__.py
@@ -0,0 +1,13 @@
+# 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.
+
+from . import check
+from . import query
diff --git a/bin/tests/system/isctest/check.py b/bin/tests/system/isctest/check.py
new file mode 100644
index 0000000000..1fabad7477
--- /dev/null
+++ b/bin/tests/system/isctest/check.py
@@ -0,0 +1,34 @@
+# 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.
+
+from typing import Any
+
+import dns.rcode
+import dns.message
+
+
+# compatiblity with dnspython<2.0.0
+try:
+    # In dnspython>=2.0.0, dns.rcode.Rcode class is available
+    # pylint: disable=invalid-name
+    dns_rcode = dns.rcode.Rcode  # type: Any
+except AttributeError:
+    # In dnspython<2.0.0, selected rcodes are available as integers directly
+    # from dns.rcode
+    dns_rcode = dns.rcode
+
+
+def rcode(message: dns.message.Message, expected_rcode) -> None:
+    assert message.rcode() == expected_rcode, str(message)
+
+
+def noerror(message: dns.message.Message) -> None:
+    rcode(message, dns_rcode.NOERROR)
diff --git a/bin/tests/system/isctest/query.py b/bin/tests/system/isctest/query.py
new file mode 100644
index 0000000000..5da1ef8423
--- /dev/null
+++ b/bin/tests/system/isctest/query.py
@@ -0,0 +1,35 @@
+# 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 os
+from typing import Optional
+
+import dns.query
+import dns.message
+
+
+QUERY_TIMEOUT = 10
+
+
+def udp(
+    message: dns.message.Message, ip: str, port: Optional[int] = None
+) -> dns.message.Message:
+    if port is None:
+        port = int(os.environ["PORT"])
+    return dns.query.udp(message, ip, QUERY_TIMEOUT, port=port)
+
+
+def tcp(
+    message: dns.message.Message, ip: str, port: Optional[int] = None
+) -> dns.message.Message:
+    if port is None:
+        port = int(os.environ["PORT"])
+    return dns.query.tcp(message, ip, QUERY_TIMEOUT, port=port)
diff --git a/dangerfile.py b/dangerfile.py
index 1d077d2ce0..ee77f13cd1 100644
--- a/dangerfile.py
+++ b/dangerfile.py
@@ -462,6 +462,7 @@ for testname in testnames:
         not os.path.isdir(dirpath)
         or testname.startswith(".")
         or testname.startswith("_")
+        or testname == "isctest"
     ):
         continue
     if "_" in testname: