GH-3732 add unit tests for Mqttv5PahoMessageDrivenChannelAdapter

Author: mipo256

spring-integration-mqtt/src/main/java/org/springframework/integration/mqtt/inbound/Mqttv5PahoMessageDrivenChannelAdapter.java

@@ -142,25 +142,23 @@ public void setHeaderMapper(HeaderMapper<MqttProperties> headerMapper) {
 	@Override
 	protected void onInit() {
 		super.onInit();
-		initializeMqttAsyncClientIfRequired();
+		if (mqttClient == null) {
+			try {
+				this.mqttClient = new MqttAsyncClient(getUrl(), getClientId(), this.persistence);
+				this.mqttClient.setCallback(this);
+				this.mqttClient.setManualAcks(isManualAcks());
+			}
+			catch (MqttException ex) {
+				throw new BeanCreationException("Cannot create 'MqttAsyncClient' for: " + getComponentName(), ex);
+			}
+		}
 		if (this.messageConverter == null) {
 			setMessageConverter(getBeanFactory()
 					.getBean(IntegrationContextUtils.ARGUMENT_RESOLVER_MESSAGE_CONVERTER_BEAN_NAME,
 							SmartMessageConverter.class));
 		}
 	}
 
-	private void initializeMqttAsyncClient() {
-		try {
-			this.mqttClient = new MqttAsyncClient(getUrl(), getClientId(), this.persistence);
-			this.mqttClient.setCallback(this);
-			this.mqttClient.setManualAcks(isManualAcks());
-		}
-		catch (MqttException ex) {
-			throw new BeanCreationException("Cannot create 'MqttAsyncClient' for: " + getComponentName(), ex);
-		}
-	}
-
 	@Override
 	protected void doStart() {
 		ApplicationEventPublisher applicationEventPublisher = getApplicationEventPublisher();
@@ -209,12 +207,6 @@ protected void doStop() {
 		}
 	}
 
-	private void initializeMqttAsyncClientIfRequired() {
-		if (mqttClient == null) {
-			initializeMqttAsyncClient();
-		}
-	}
-
 	@Override
 	public void destroy() {
 		super.destroy();
@@ -231,11 +223,11 @@ public void destroy() {
 	public void addTopic(String topic, int qos) {
 		this.topicLock.lock();
 		try {
+			super.addTopic(topic, qos);
 			if (mqttClient != null && mqttClient.isConnected()) {
 				this.mqttClient.subscribe(topic, qos).waitForCompletion(getCompletionTimeout());
-				super.addTopic(topic, qos);
 			} else {
-				logger.warn(String.format("An attempt to add topic : '%s' with QoS : '%s' without having mqtt client initialized or connected, the topic will not be added!", topic, qos));
+				logger.warn(String.format("An attempt to add topic : '%s' with QoS : '%s' without having mqtt client initialized or connected", topic, qos));
 			}
 		}
 		catch (MqttException ex) {

spring-integration-mqtt/src/test/java/org/springframework/integration/mqtt/inbound/Mqttv5PahoMessageDrivenChannelAdapterTest.java

@@ -0,0 +1,24 @@
+package org.springframework.integration.mqtt.inbound;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Mqttv5PahoMessageDrivenChannelAdapterTest's unit tests
+ *
+ * @author Mikhail Polivakha
+ */
+class Mqttv5PahoMessageDrivenChannelAdapterTest {
+
+	@Test //GH-3732
+	public void testNoNpeIsNotThrownInCaseDoInitIsNotInvokedBeforeTopicAddition() {
+		Mqttv5PahoMessageDrivenChannelAdapter channelAdapter = new Mqttv5PahoMessageDrivenChannelAdapter("tcp://mock-url.com:8091", "mock-client-id", "123");
+		Assertions.assertDoesNotThrow(() -> channelAdapter.addTopic("abc", 1));
+	}
+
+	@Test //GH-3732
+	public void testNoNpeIsNotThrownInCaseDoInitIsNotInvokedBeforeTopicRemoval() {
+		Mqttv5PahoMessageDrivenChannelAdapter channelAdapter = new Mqttv5PahoMessageDrivenChannelAdapter("tcp://mock-url.com:8091", "mock-client-id", "123");
+		Assertions.assertDoesNotThrow(() -> channelAdapter.removeTopic("abc"));
+	}
+}