Merge pull request #14807 from Marcus Eisele

* gh-14807:
  Polish "Add Log Output when DevTools restart is disabled"
  Add Log Output when DevTools restart is disabled

spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/restart/RestartApplicationListener.java

 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,9 @@
 
 package org.springframework.boot.devtools.restart;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
 import org.springframework.boot.context.event.ApplicationFailedEvent;
 import org.springframework.boot.context.event.ApplicationPreparedEvent;
 import org.springframework.boot.context.event.ApplicationReadyEvent;
@@ -35,10 +38,12 @@ import org.springframework.core.Ordered;
 public class RestartApplicationListener
 		implements ApplicationListener<ApplicationEvent>, Ordered {
 
-	private int order = HIGHEST_PRECEDENCE;
-
 	private static final String ENABLED_PROPERTY = "spring.devtools.restart.enabled";
 
+	private static final Log logger = LogFactory.getLog(RestartApplicationListener.class);
+
+	private int order = HIGHEST_PRECEDENCE;
+
 	@Override
 	public void onApplicationEvent(ApplicationEvent event) {
 		if (event instanceof ApplicationStartingEvent) {
@@ -64,9 +69,15 @@ public class RestartApplicationListener
 			String[] args = event.getArgs();
 			DefaultRestartInitializer initializer = new DefaultRestartInitializer();
 			boolean restartOnInitialize = !AgentReloader.isActive();
+			if (!restartOnInitialize) {
+				logger.info(
+						"Restart disabled due to an agent-based reloader being active");
+			}
 			Restarter.initialize(args, false, initializer, restartOnInitialize);
 		}
 		else {
+			logger.info("Restart disabled due to System property '" + ENABLED_PROPERTY
+					+ "' being set to false");
 			Restarter.disable();
 		}
 	}

spring-boot-project/spring-boot-devtools/src/test/java/org/springframework/boot/devtools/restart/RestartApplicationListenerTests.java

@@ -20,6 +20,7 @@ import java.util.List;
 
 import org.junit.After;
 import org.junit.Before;
+import org.junit.Rule;
 import org.junit.Test;
 
 import org.springframework.boot.SpringApplication;
@@ -27,6 +28,7 @@ import org.springframework.boot.context.event.ApplicationFailedEvent;
 import org.springframework.boot.context.event.ApplicationPreparedEvent;
 import org.springframework.boot.context.event.ApplicationReadyEvent;
 import org.springframework.boot.context.event.ApplicationStartingEvent;
+import org.springframework.boot.test.rule.OutputCapture;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.core.Ordered;
 import org.springframework.test.util.ReflectionTestUtils;
@@ -47,6 +49,9 @@ public class RestartApplicationListenerTests {
 
 	private static final String[] ARGS = new String[] { "a", "b", "c" };
 
+	@Rule
+	public final OutputCapture output = new OutputCapture();
+
 	@Before
 	@After
 	public void cleanup() {
@@ -81,8 +86,11 @@ public class RestartApplicationListenerTests {
 	@Test
 	public void disableWithSystemProperty() {
 		System.setProperty(ENABLED_PROPERTY, "false");
+		this.output.reset();
 		testInitialize(false);
 		assertThat(Restarter.getInstance()).hasFieldOrPropertyWithValue("enabled", false);
+		assertThat(this.output.toString())
+				.contains("Restart disabled due to System property");
 	}
 
 	private void testInitialize(boolean failed) {