diff --git a/dist/pythonlibs/riotctrl_shell/congure_test.py b/dist/pythonlibs/riotctrl_shell/congure_test.py
new file mode 100644
index 000000000000..5028fc0ae3af
--- /dev/null
+++ b/dist/pythonlibs/riotctrl_shell/congure_test.py
@@ -0,0 +1,111 @@
+# Copyright (C) 2021 Freie Universität Berlin
+#
+# This file is subject to the terms and conditions of the GNU Lesser
+# General Public License v2.1. See the file LICENSE in the top level
+# directory for more details.
+
+"""
+`congure_test`-related shell interactions
+
+Defines `congure_test`-related shell command interactions
+"""
+
+from riotctrl.shell import ShellInteraction
+
+
+class CongureTest(ShellInteraction):
+    @ShellInteraction.check_term
+    def setup(self, ident=0, timeout=-1, async_=False):
+        return self.cmd('cong_setup {ident}'.format(ident=ident),
+                        timeout=timeout, async_=async_)
+
+    @ShellInteraction.check_term
+    def clear(self, timeout=-1, async_=False):
+        return self.cmd('cong_clear', timeout=timeout, async_=async_)
+
+    @ShellInteraction.check_term
+    def init(self, ctx, timeout=-1, async_=False):
+        return self.cmd('cong_init 0x{ctx:x}'.format(ctx=ctx),
+                        timeout=timeout, async_=async_)
+
+    @ShellInteraction.check_term
+    def inter_msg_interval(self, msg_size, timeout=-1, async_=False):
+        return self.cmd('cong_imi {msg_size}'.format(msg_size=msg_size),
+                        timeout=timeout, async_=async_)
+
+    @ShellInteraction.check_term
+    def add_msg(self, send_time, size, resends, timeout=-1, async_=False):
+        return self.cmd(
+            'cong_add_msg {send_time} {size} {resends}'
+            .format(send_time=send_time, size=size, resends=resends)
+        )
+
+    @ShellInteraction.check_term
+    def msgs_reset(self, timeout=-1, async_=False):
+        return self.cmd('cong_msgs_reset')
+
+    @ShellInteraction.check_term
+    def report(self, cmd, *args, timeout=-1, async_=False):
+        args = ' '.join(str(a) for a in args)
+        return self.cmd('cong_report {cmd} {args}'.format(cmd=cmd, args=args))
+
+    def report_msg_sent(self, msg_size, timeout=-1, async_=False):
+        return self.report('msg_sent', msg_size,
+                           timeout=timeout, async_=async_)
+
+    def report_msg_discarded(self, msg_size, timeout=-1, async_=False):
+        return self.report('msg_discarded', msg_size,
+                           timeout=timeout, async_=async_)
+
+    def _report_msgs_timeout_lost_base(self, cmd, timeout=-1, async_=False):
+        return self.report(cmd, timeout=timeout, async_=async_)
+
+    def _report_msgs_timeout_lost(self, cmd, msgs, timeout=-1, async_=False):
+        tmp = None
+        for msg in msgs:
+            tmp = self.add_msg(**msg)
+            assert 'success' in tmp
+        res = self._report_msgs_timeout_lost_base(
+            cmd, timeout=timeout, async_=async_
+        )
+        return res
+
+    def report_msgs_timeout_base(self, timeout=-1, async_=False):
+        return self._report_msgs_timeout_lost_base(
+            'msgs_timeout', timeout=timeout, async_=async_
+        )
+
+    def report_msgs_timeout(self, msgs, timeout=-1, async_=False):
+        return self._report_msgs_timeout_lost(
+            'msgs_timeout', msgs, timeout=timeout, async_=async_
+        )
+
+    def report_msgs_lost_base(self, timeout=-1, async_=False):
+        return self._report_msgs_timeout_lost_base(
+            'msgs_lost', timeout=timeout, async_=async_
+        )
+
+    def report_msgs_lost(self, msgs, timeout=-1, async_=False):
+        return self._report_msgs_timeout_lost(
+            'msgs_lost', msgs, timeout=timeout, async_=async_
+        )
+
+    def report_msg_acked_base(self, ack_recv_time, ack_id, ack_size, ack_clean,
+                              ack_wnd, ack_delay, timeout=-1, async_=False):
+        if isinstance(ack_clean, bool):
+            ack_clean = int(ack_clean)
+        return self.report('msg_acked', ack_recv_time, ack_id, ack_size,
+                           ack_clean, ack_wnd, ack_delay,
+                           timeout=-1, async_=False)
+
+    def report_msg_acked(self, msg, ack, timeout=-1, async_=False):
+        tmp = self.add_msg(**msg)
+        assert 'success' in tmp
+        res = self.report_msg_acked_base(
+            **{'ack_{}'.format(k): v for k, v in ack.items()},
+            timeout=timeout, async_=async_
+        )
+        return res
+
+    def report_ecn_ce(self, time, timeout=-1, async_=False):
+        return self.report('ecn_ce', time, timeout=timeout, async_=async_)
diff --git a/dist/pythonlibs/riotctrl_shell/tests/common.py b/dist/pythonlibs/riotctrl_shell/tests/common.py
index 348c90c5b1ef..342fb1be7486 100644
--- a/dist/pythonlibs/riotctrl_shell/tests/common.py
+++ b/dist/pythonlibs/riotctrl_shell/tests/common.py
@@ -10,17 +10,25 @@
 class MockSpawn():
     def __init__(self, ctrl, *args, **kwargs):
         self.ctrl = ctrl
-        self.last_command = None
+        self.commands = []
         # set some expected attributes
         self.before = None
         self.echo = False
 
+    @property
+    def last_command(self):
+        if self.commands:
+            return self.commands[-1]
+        else:
+            return None
+
     def read_nonblocking(self, size=1, timeout=-1):
         # do nothing, only used to flush pexpect output
         pass
 
     def sendline(self, line, *args, **kwargs):
-        self.last_command = line
+        if line:
+            self.commands.append(line)
         if self.ctrl.output is None:
             # just echo last input for before (what replwrap is assembling
             # output from)
diff --git a/dist/pythonlibs/riotctrl_shell/tests/test_congure_test.py b/dist/pythonlibs/riotctrl_shell/tests/test_congure_test.py
new file mode 100644
index 000000000000..a1b630bd5f14
--- /dev/null
+++ b/dist/pythonlibs/riotctrl_shell/tests/test_congure_test.py
@@ -0,0 +1,130 @@
+# Copyright (C) 2021 Freie Universität Berlin
+#
+# This file is subject to the terms and conditions of the GNU Lesser
+# General Public License v2.1. See the file LICENSE in the top level
+# directory for more details.
+
+import pytest
+import riotctrl_shell.congure_test
+
+from .common import init_ctrl
+
+
+@pytest.fixture
+def shell():
+    rc = init_ctrl()
+    yield riotctrl_shell.congure_test.CongureTest(rc)
+
+
+@pytest.fixture
+def success_shell():
+    rc = init_ctrl()
+    rc.output = '{"success":null}'
+    yield riotctrl_shell.congure_test.CongureTest(rc)
+
+
+def test_congure_setup(shell):
+    res = shell.setup(0)
+    assert res == 'cong_setup 0'
+
+
+def test_congure_clear(shell):
+    res = shell.clear()
+    assert res == 'cong_clear'
+
+
+def test_congure_init(shell):
+    res = shell.init(0xabcdef)
+    assert res == 'cong_init 0xabcdef'
+
+
+def test_congure_inter_msg_interval(shell):
+    res = shell.inter_msg_interval(12345)
+    assert res == 'cong_imi 12345'
+
+
+def test_congure_add_msg(shell):
+    res = shell.add_msg(send_time=543234, size=664343, resends=43)
+    assert res == 'cong_add_msg 543234 664343 43'
+
+
+def test_congure_msgs_reset(shell):
+    res = shell.msgs_reset()
+    assert res == 'cong_msgs_reset'
+
+
+def test_congure_report(shell):
+    res = shell.report('foobar', 'a', 'b', 'c')
+    assert res == 'cong_report foobar a b c'
+
+
+def test_congure_report_msg_sent(shell):
+    res = shell.report_msg_sent(12364)
+    assert res == 'cong_report msg_sent 12364'
+
+
+def test_congure_report_msg_discarded(shell):
+    res = shell.report_msg_discarded(12364)
+    assert res == 'cong_report msg_discarded 12364'
+
+
+def test_congure_report_msgs_lost_base(shell):
+    res = shell.report_msgs_lost_base()
+    assert res == 'cong_report msgs_lost '
+
+
+def test_congure_report_msgs_lost(success_shell):
+    res = success_shell.report_msgs_lost([
+        {'send_time': 1545245236, 'size': 12434, 'resends': 32},
+        {'send_time': 175344346, 'size': 34323, 'resends': 42},
+    ])
+    assert res == '{"success":null}'
+    assert success_shell.riotctrl.term.commands == [
+        'cong_add_msg 1545245236 12434 32',
+        'cong_add_msg 175344346 34323 42',
+        'cong_report msgs_lost ',
+    ]
+
+
+def test_congure_report_msgs_timeout_base(shell):
+    res = shell.report_msgs_timeout_base()
+    assert res == 'cong_report msgs_timeout '
+
+
+def test_congure_report_msgs_timeout(success_shell):
+    res = success_shell.report_msgs_timeout([
+        {'send_time': 1545245236, 'size': 12434, 'resends': 32},
+        {'send_time': 175344346, 'size': 34323, 'resends': 42},
+    ])
+    assert res == '{"success":null}'
+    assert success_shell.riotctrl.term.commands == [
+        'cong_add_msg 1545245236 12434 32',
+        'cong_add_msg 175344346 34323 42',
+        'cong_report msgs_timeout ',
+    ]
+
+
+def test_congure_report_msg_acked_base(shell):
+    res = shell.report_msg_acked_base(
+        ack_recv_time=12354356, ack_id=4314, ack_size=5632, ack_clean=True,
+        ack_wnd=45645, ack_delay=12345
+    )
+    assert res == 'cong_report msg_acked 12354356 4314 5632 1 45645 12345'
+
+
+def test_congure_report_msg_acked(success_shell):
+    res = success_shell.report_msg_acked(
+        msg={'send_time': 325242435, 'size': 34321, 'resends': 4},
+        ack={'recv_time': 325243543, 'id': 455763452, 'size': 4242,
+             'clean': 0, 'wnd': 45645, 'delay': 12345},
+    )
+    assert res == '{"success":null}'
+    assert success_shell.riotctrl.term.commands == [
+        'cong_add_msg 325242435 34321 4',
+        'cong_report msg_acked 325243543 455763452 4242 0 45645 12345',
+    ]
+
+
+def test_congure_report_ecn_ce(shell):
+    res = shell.report_ecn_ce(583424522)
+    assert res == 'cong_report ecn_ce 583424522'
diff --git a/tests/congure_test/README.md b/tests/congure_test/README.md
index 656a441c767d..3fa8a2df80da 100644
--- a/tests/congure_test/README.md
+++ b/tests/congure_test/README.md
@@ -22,7 +22,7 @@ $ BOARD="<board>" make flash test
 It can also executed with pytest:
 
 ```console
-$ pytest tests/01-run.py
+$ PYTHONPATH=../../dist/pythonlibs BOARD="<board>" pytest tests/01-run.py
 ```
 
 Note that this only works from within the directory of the test, so if you are
diff --git a/tests/congure_test/tests/01-run.py b/tests/congure_test/tests/01-run.py
index ea58fc8d9055..5fc8ef090166 100755
--- a/tests/congure_test/tests/01-run.py
+++ b/tests/congure_test/tests/01-run.py
@@ -15,6 +15,8 @@
 from riotctrl.shell import ShellInteraction
 from riotctrl.shell.json import RapidJSONShellInteractionParser, rapidjson
 
+from riotctrl_shell.congure_test import CongureTest
+
 
 class TestCongUREBase(unittest.TestCase):
     DEBUG = False
@@ -485,5 +487,165 @@ def test_report_ecn_ce_success(self):
                          time)
 
 
+class TestCongUREWithCongureTestSI(TestCongUREBase):
+    @classmethod
+    def setUpClass(cls):
+        super(cls, cls).setUpClass()
+        cls.shell = CongureTest(cls.ctrl)
+
+    def call_method(self, method, *args, timeout=-1, async_=False, **kwargs):
+        res = getattr(self.shell, method)(*args,
+                                          timeout=timeout, async_=async_,
+                                          **kwargs)
+        self.logger.debug(repr(res))
+        if res.strip():
+            return self.json_parser.parse(res)
+        return None
+
+    def setUp(self):
+        super().setUp()
+        res = self.call_method('setup')
+        self.congure_state_ptr = int(res['success'], base=16)
+
+    def tearDown(self):
+        res = self.call_method('msgs_reset')
+        self.assertIn('success', res)
+
+    def test_init_success(self):
+        ctx = 0x12345
+        res = self.call_method('init', ctx=ctx)
+        self.assertIsNone(res['success'])
+        res = self.exec_cmd('state')
+        self.assertEqual(res['init']['calls'], 1)
+        self.assertEqual(int(res['init']['last_args']['c'], base=16),
+                         self.congure_state_ptr)
+        self.assertEqual(int(res['init']['last_args']['ctx'], base=16),
+                         ctx)
+
+    def test_inter_msg_interval_success(self):
+        msg_size = 521
+        res = self.call_method('inter_msg_interval', msg_size=msg_size)
+        assert res == {'success': -1}
+        res = self.exec_cmd('state')
+        self.assertEqual(res['inter_msg_interval']['calls'], 1)
+        self.assertEqual(int(res['inter_msg_interval']['last_args']['c'],
+                             base=16),
+                         self.congure_state_ptr)
+        self.assertEqual(res['inter_msg_interval']['last_args']['msg_size'],
+                         msg_size)
+
+    def test_report_unknown_command(self):
+        res = self.call_method('report', 'foobar')
+        self.assertEqual(res, {'error': 'Unknown command `foobar`'})
+
+    def test_report_msg_sent_success(self):
+        msg_size = 1234
+        res = self.call_method('report_msg_sent', msg_size=msg_size)
+        self.assertIsNone(res['success'])
+        res = self.exec_cmd('state')
+        self.assertEqual(res['report_msg_sent']['calls'], 1)
+        self.assertEqual(int(res['report_msg_sent']['last_args']['c'],
+                             base=16),
+                         self.congure_state_ptr)
+        self.assertEqual(res['report_msg_sent']['last_args']['msg_size'],
+                         msg_size)
+
+    def test_report_msg_discarded_success(self):
+        msg_size = 1234
+        res = self.call_method('report_msg_discarded', msg_size=msg_size)
+        self.assertIsNone(res['success'])
+        res = self.exec_cmd('state')
+        self.assertEqual(res['report_msg_discarded']['calls'], 1)
+        self.assertEqual(int(res['report_msg_discarded']['last_args']['c'],
+                             base=16),
+                         self.congure_state_ptr)
+        self.assertEqual(res['report_msg_discarded']['last_args']['msg_size'],
+                         msg_size)
+
+    def _report_msgs_timeout_lost_base_success(self, cmd):
+        msgs = [{'send_time': 76543, 'size': 1234, 'resends': 2},
+                {'send_time': 5432, 'size': 987, 'resends': 32}]
+        for msg in msgs:
+            res = self.call_method('add_msg', **msg)
+        res = self.call_method('report_{}_base'.format(cmd))
+        self.assertIsNone(res['success'])
+        res = self.exec_cmd('state')
+        self.assertEqual(res['report_{}'.format(cmd)]['calls'], 1)
+        self.assertEqual(int(res['report_{}'.format(cmd)]['last_args']['c'],
+                             base=16),
+                         self.congure_state_ptr)
+        self.assertEqual(res['report_{}'.format(cmd)]['last_args']['msgs'],
+                         msgs)
+
+    def _report_msgs_timeout_lost_success(self, cmd):
+        msgs = [{'send_time': 76543, 'size': 1234, 'resends': 2},
+                {'send_time': 5432, 'size': 987, 'resends': 32}]
+        res = self.call_method('report_{}'.format(cmd), msgs=msgs)
+        self.assertIsNone(res['success'])
+        res = self.exec_cmd('state')
+        self.assertEqual(res['report_{}'.format(cmd)]['calls'], 1)
+        self.assertEqual(int(res['report_{}'.format(cmd)]['last_args']['c'],
+                             base=16),
+                         self.congure_state_ptr)
+        self.assertEqual(res['report_{}'.format(cmd)]['last_args']['msgs'],
+                         msgs)
+
+    def test_report_msgs_timeout_base_success(self):
+        self._report_msgs_timeout_lost_base_success('msgs_timeout')
+
+    def test_report_msgs_lost_base_success(self):
+        self._report_msgs_timeout_lost_base_success('msgs_lost')
+
+    def test_report_msgs_timeout_success(self):
+        self._report_msgs_timeout_lost_success('msgs_timeout')
+
+    def test_report_msgs_lost_success(self):
+        self._report_msgs_timeout_lost_success('msgs_lost')
+
+    def test_report_msg_acked_base_success(self):
+        msg = {'send_time': 2862350241, 'size': 14679, 'resends': 0}
+        ack = {'recv_time': 2862350405, 'id': 1197554483, 'size': 14667,
+               'clean': 1, 'wnd': 17440, 'delay': 33325}
+        res = self.call_method('add_msg', **msg)
+        self.assertIn('success', res)
+        res = self.call_method(
+            'report_msg_acked_base',
+            **{'ack_{}'.format(k): v for k, v in ack.items()})
+        self.assertIsNone(res['success'])
+        res = self.exec_cmd('state')
+        self.assertEqual(res['report_msg_acked']['calls'], 1)
+        self.assertEqual(int(res['report_msg_acked']['last_args']['c'],
+                             base=16),
+                         self.congure_state_ptr)
+        self.assertEqual(res['report_msg_acked']['last_args']['msg'], msg)
+        self.assertEqual(res['report_msg_acked']['last_args']['ack'], ack)
+
+    def test_report_msg_acked_success(self):
+        msg = {'send_time': 2862350241, 'size': 14679, 'resends': 0}
+        ack = {'recv_time': 2862350405, 'id': 1197554483, 'size': 14667,
+               'clean': 1, 'wnd': 17440, 'delay': 33325}
+        res = self.call_method('report_msg_acked', msg=msg, ack=ack)
+        self.assertIsNone(res['success'])
+        res = self.exec_cmd('state')
+        self.assertEqual(res['report_msg_acked']['calls'], 1)
+        self.assertEqual(int(res['report_msg_acked']['last_args']['c'],
+                             base=16),
+                         self.congure_state_ptr)
+        self.assertEqual(res['report_msg_acked']['last_args']['msg'], msg)
+        self.assertEqual(res['report_msg_acked']['last_args']['ack'], ack)
+
+    def test_report_ecn_ce_success(self):
+        time = 64352
+        res = self.call_method('report_ecn_ce', time=time)
+        self.assertIsNone(res['success'])
+        res = self.exec_cmd('state')
+        self.assertEqual(res['report_ecn_ce']['calls'], 1)
+        self.assertEqual(int(res['report_ecn_ce']['last_args']['c'],
+                             base=16),
+                         self.congure_state_ptr)
+        self.assertEqual(res['report_ecn_ce']['last_args']['time'],
+                         time)
+
+
 if __name__ == '__main__':
     unittest.main()