Make the Maven plugin’s start and stop tests more robust

 - Verify that isReady has been called
 - When forking, use a random port for JMX
 - Don’t wait for application termination as it introduces a race
   condition and verifying that shutdown has been requested is
   sufficient

See gh-2525

spring-boot-tools/spring-boot-maven-plugin/src/it/start-stop-fork/pom.xml

@@ -10,6 +10,24 @@
 	</properties>
 	<build>
 		<plugins>
+			<plugin>
+				<groupId>org.codehaus.mojo</groupId>
+				<artifactId>build-helper-maven-plugin</artifactId>
+				<executions>
+					<execution>
+						<id>reserve-jmx-port</id>
+						<goals>
+							<goal>reserve-network-port</goal>
+						</goals>
+						<phase>process-resources</phase>
+						<configuration>
+							<portNames>
+								<portName>jmx.port</portName>
+							</portNames>
+						</configuration>
+					</execution>
+				</executions>
+			</plugin>
 			<plugin>
 				<groupId>@project.groupId@</groupId>
 				<artifactId>@project.artifactId@</artifactId>
@@ -30,6 +48,7 @@
 				</executions>
 				<configuration>
 					<fork>true</fork>
+					<jmxPort>${jmx.port}</jmxPort>
 				</configuration>
 			</plugin>
 		</plugins>

spring-boot-tools/spring-boot-maven-plugin/src/it/start-stop-fork/src/main/java/org/test/SampleApplication.java

@@ -17,6 +17,7 @@
 package org.test;
 
 import java.lang.management.ManagementFactory;
+
 import javax.management.MBeanServer;
 import javax.management.ObjectName;
 
@@ -47,7 +48,6 @@ public class SampleApplication {
 			}
 			waitAttempts++;
 		}
-		System.out.println("Application has terminated gracefully");
 	}
 
 
@@ -67,6 +67,7 @@ public class SampleApplication {
 
 		@Override
 		public boolean isReady() {
+			System.out.println("isReady: " + this.ready);
 			return this.ready;
 		}
 

spring-boot-tools/spring-boot-maven-plugin/src/it/start-stop-fork/verify.groovy

 import static org.junit.Assert.assertTrue
 
 def file = new File(basedir, "build.log")
+assertTrue 'Start should have waited for application to be ready', file.text.contains("isReady: true")
 assertTrue 'Shutdown should have been invoked', file.text.contains("Shutdown requested")
-assertTrue 'Application should have terminated', file.text.contains("Application has terminated gracefully")
-

spring-boot-tools/spring-boot-maven-plugin/src/it/start-stop/src/main/java/org/test/SampleApplication.java

@@ -47,7 +47,6 @@ public class SampleApplication {
 			}
 			waitAttempts++;
 		}
-		System.out.println("Application has terminated gracefully");
 	}
 
 
@@ -67,6 +66,7 @@ public class SampleApplication {
 
 		@Override
 		public boolean isReady() {
+			System.out.println("isReady: " + this.ready);
 			return this.ready;
 		}
 

spring-boot-tools/spring-boot-maven-plugin/src/it/start-stop/verify.groovy

 import static org.junit.Assert.assertTrue
 
 def file = new File(basedir, "build.log")
+assertTrue 'Start should have waited for application to be ready', file.text.contains("isReady: true")
 assertTrue 'Shutdown should have been invoked', file.text.contains("Shutdown requested")
-assertTrue 'Application should have terminated', file.text.contains("Application has terminated gracefully")
-