ZeroMQ test: Add sleep between SUB & PUB

Author: artembilan

spring-integration-zeromq/src/test/java/org/springframework/integration/zeromq/outbound/ZeroMqMessageHandlerTests.java

@@ -86,7 +86,7 @@ void testMessageHandlerForPair() {
 	}
 
 	@Test
-	void testMessageHandlerForPubSub() {
+	void testMessageHandlerForPubSub() throws InterruptedException {
 		ZMQ.Socket subSocket = CONTEXT.createSocket(SocketType.SUB);
 		subSocket.setReceiveTimeOut(20_000);
 		int port = subSocket.bindToRandomPort("tcp://*");
@@ -98,12 +98,15 @@ void testMessageHandlerForPubSub() {
 				new FunctionExpression<Message<?>>((message) -> message.getHeaders().get("topic")));
 		messageHandler.setMessageMapper(new EmbeddedJsonHeadersMessageMapper());
 		messageHandler.afterPropertiesSet();
+		subSocket.subscribe("test");
+
+		// Give it some time to connect and subscribe
+		Thread.sleep(2000);
 
 		Message<?> testMessage = MessageBuilder.withPayload("test").setHeader("topic", "testTopic").build();
 
 		await().atMost(Duration.ofSeconds(20)).pollDelay(Duration.ofMillis(100))
 				.untilAsserted(() -> {
-					subSocket.subscribe("test");
 					messageHandler.handleMessage(testMessage).subscribe();
 					ZMsg msg = ZMsg.recvMsg(subSocket);
 					assertThat(msg).isNotNull();