Add proposed syntax for handling subscriptions

osbrain/tests/test_agent_pubsub_topics.py

@@ -1,9 +1,11 @@
 import time
 
 import pytest
+import zmq
 
 from osbrain import run_agent
 from osbrain.address import AgentAddressSerializer
+from osbrain.helper import wait_agent_attr
 
 from common import nsproxy  # pragma: no flakes
 
@@ -12,6 +14,40 @@ def log_received_to_list(agent, message, topic=None):
     agent.received_list.append(message)
 
 
+def test_change_subscription_topics(nsproxy):
+    '''
+    Test for the different options of subscribing/unsubscribing to topics
+    in the PUB/SUB pattern.
+    '''
+    server = run_agent('server')
+    client = run_agent('client')
+
+    addr = server.bind('PUB', alias='pub')
+    client.set_attr(received_list=[])
+    client.connect(addr, alias='sub', handler=log_received_to_list)
+
+    # Stablish a connection
+    server.each(0.1, 'send', 'pub', 'connecting...')
+    assert wait_agent_attr(client, name='received_list', data='connecting...')
+
+    # By default, client will be subscribed to all topics
+    server.send('pub', 'hello')
+    assert wait_agent_attr(client, name='received_list', data='hello')
+
+    # Only subscribe to 'TOP' topic
+    client.unsubscribe_socket_from_topic('sub', b'')
+    client.subscribe_socket_to_topic('sub', b'TOP')
+
+    # Message not received since 'TOP' topic not specified in the send call
+    server.send('pub', 'world')
+    assert not wait_agent_attr(client, name='received_list', data='world',
+                               timeout=1)
+
+    # Receive message with the topic we are subscribed to
+    server.send('pub', 'ten', topic='TOP')
+    assert wait_agent_attr(client, name='received_list', data='ten')
+
+
 @pytest.mark.parametrize(
     'serializer',
     AgentAddressSerializer.SERIALIZER_SEPARATOR