diff --git a/pytest.ini b/pytest.ini
new file mode 100644
index 0000000..72a218a
--- /dev/null
+++ b/pytest.ini
@@ -0,0 +1,2 @@
+[pytest]
+filterwarnings = ignore::DeprecationWarning:zmq
diff --git a/tfw/internals/networking/test_networking.py b/tfw/internals/networking/test_networking.py
new file mode 100644
index 0000000..cc23069
--- /dev/null
+++ b/tfw/internals/networking/test_networking.py
@@ -0,0 +1,106 @@
+# pylint: disable=redefined-outer-name
+from os.path import join
+from secrets import token_urlsafe
+from random import randint
+from tempfile import TemporaryDirectory
+
+import pytest
+from tornado.ioloop import IOLoop
+
+from tfw.internals.networking import EventHandlerConnector, ServerConnector
+
+
+@pytest.fixture
+def _connectors():
+    with TemporaryDirectory() as tmpdir:
+        down_sock = join(tmpdir, 'down')
+        up_sock = join(tmpdir, 'up')
+        server_downlink = f'ipc://{down_sock}'
+        server_uplink = f'ipc://{up_sock}'
+
+        ec = EventHandlerConnector(server_downlink, server_uplink)
+        sc = ServerConnector(server_uplink, server_downlink)
+        yield ec, sc
+        sc.close()
+        ec.close()
+
+
+@pytest.fixture
+def eh_connector(_connectors):
+    eh_connector, _ = _connectors
+    yield eh_connector
+
+
+@pytest.fixture
+def server_connector(_connectors):
+    _, server_connector = _connectors
+    yield server_connector
+
+
+def run_ioloop_once():
+    # hack: we have to wait for the messages to get through
+    # the network stack of the OS while the IOLoop is waiting
+    # for them via select/epoll/kqueue
+    IOLoop.current().call_later(0.1, IOLoop.current().stop)
+    IOLoop.current().start()
+
+
+@pytest.fixture
+def test_messages():
+    random_str = lambda: token_urlsafe(randint(4, 8))
+    yield [
+        {
+            'key': random_str(),
+            random_str(): randint(8192, 16384),
+            random_str(): random_str(),
+            random_str(): {
+                random_str(): random_str(),
+                random_str(): {random_str(): random_str()}
+            },
+            random_str(): [random_str(), random_str()]
+        }
+        for _ in range(randint(8, 16))
+    ]
+
+
+def test_server_downlink(eh_connector, server_connector, test_messages):
+    messages = []
+    eh_connector.register_callback(messages.append)
+
+    for message in test_messages:
+        server_connector.send_message(message)
+
+    run_ioloop_once()
+
+    assert messages == test_messages
+
+
+def test_server_uplink(eh_connector, server_connector, test_messages):
+    messages = []
+    server_connector.subscribe('')
+    server_connector.register_callback(messages.append)
+
+    for message in test_messages:
+        eh_connector.send_message(message)
+
+    run_ioloop_once()
+
+    assert messages == test_messages
+
+
+def test_connector_downlink_subscribe(eh_connector, server_connector):
+    key1_messages = [{'key': '1', 'data': i} for i in range(randint(128, 256))]
+    key2_messages = [{'key': '2', 'data': i} for i in range(randint(128, 256))]
+    all_messages = key1_messages + key2_messages
+
+    messages = []
+    server_connector.subscribe('1')
+    server_connector.register_callback(messages.append)
+
+    for message in all_messages:
+        eh_connector.send_message(message)
+
+    run_ioloop_once()
+
+    assert messages == key1_messages
+    assert all((msg not in messages for msg in key2_messages))