zmq test: dedup message reception handling in ZMQSubscriber

Author: theStack

test/functional/interface_zmq.py

@@ -33,7 +33,8 @@ def __init__(self, socket, topic):
 
         self.socket.setsockopt(zmq.SUBSCRIBE, self.topic)
 
-    def receive(self):
+    # Receive message from publisher and verify that topic and sequence match
+    def _receive_from_publisher_and_check(self):
         topic, body, seq = self.socket.recv_multipart()
         # Topic should match the subscriber topic.
         assert_equal(topic, self.topic)
@@ -42,13 +43,11 @@ def receive(self):
         self.sequence += 1
         return body
 
+    def receive(self):
+        return self._receive_from_publisher_and_check()
+
     def receive_sequence(self):
-        topic, body, seq = self.socket.recv_multipart()
-        # Topic should match the subscriber topic.
-        assert_equal(topic, self.topic)
-        # Sequence should be incremental.
-        assert_equal(struct.unpack('<I', seq)[-1], self.sequence)
-        self.sequence += 1
+        body = self._receive_from_publisher_and_check()
         hash = body[:32].hex()
         label = chr(body[32])
         mempool_sequence = None if len(body) != 32+1+8 else struct.unpack("<Q", body[32+1:])[0]