test: Add zmq test to support multiple interfaces

test/functional/interface_zmq.py

@@ -75,6 +75,7 @@ class ZMQTest (BitcoinTestFramework):
             self.test_sequence()
             self.test_mempool_sync()
             self.test_reorg()
+            self.test_multiple_interfaces()
         finally:
             # Destroy the ZMQ context.
             self.log.debug("Destroying ZMQ context")
@@ -506,5 +507,28 @@ class ZMQTest (BitcoinTestFramework):
 
         self.nodes[0].generatetoaddress(1, ADDRESS_BCRT1_UNSPENDABLE)
 
+    def test_multiple_interfaces(self):
+        # Set up two subscribers with different addresses
+        subscribers = []
+        for i in range(2):
+            address = 'tcp://127.0.0.1:%d' % (28334 + i)
+            socket = self.ctx.socket(zmq.SUB)
+            socket.set(zmq.RCVTIMEO, 60000)
+            hashblock = ZMQSubscriber(socket, b"hashblock")
+            socket.connect(address)
+            subscribers.append({'address': address, 'hashblock': hashblock})
+
+        self.restart_node(0, ['-zmqpub%s=%s' % (subscriber['hashblock'].topic.decode(), subscriber['address']) for subscriber in subscribers])
+
+        # Relax so that the subscriber is ready before publishing zmq messages
+        sleep(0.2)
+
+        # Generate 1 block in nodes[0] and receive all notifications
+        self.nodes[0].generatetoaddress(1, ADDRESS_BCRT1_UNSPENDABLE)
+
+        # Should receive the same block hash on both subscribers
+        assert_equal(self.nodes[0].getbestblockhash(), subscribers[0]['hashblock'].receive().hex())
+        assert_equal(self.nodes[0].getbestblockhash(), subscribers[1]['hashblock'].receive().hex())
+
 if __name__ == '__main__':
     ZMQTest().main()