GH-973: Higher order for RabbitListTestBootstrap (#976)

* GH-973: Higher order for RabbitListTestBootstrap

Fixes https://github.com/spring-projects/spring-amqp/issues/973

When we use `@EnableRabbit` and `@RabbitListenerTest` in the same
configuration set, e.g. mixing real `@Configuration` and test one for
`@RabbitListenerTest`, we may end up with the case when `@EnableRabbit`
is processed before `@RabbitListenerTest`, so, `RabbitListenerTestHarness`
bean is not going to appear in the application context.

* Implement a `DeferredImportSelector` with an `@Order` for the
`@EnableRabbit` as well as `RabbitListenerTest` giving higher order to
the `RabbitListenerTestSelector`, so `RabbitListenerTestBootstrap` is
processed and register its `RabbitListenerTestHarness` earlier, than it
is done by the `RabbitBootstrapConfiguration`

**Cherry-pick to 2.1.x**

* * Fix Checkstyle
* Add JavaDocs to new classes

spring-rabbit-test/src/main/java/org/springframework/amqp/rabbit/test/RabbitListenerTest.java

@@ -30,6 +30,8 @@ import org.springframework.context.annotation.Import;
  * {@code @RabbitListener} beans to capture arguments and result (if any).
  *
  * @author Gary Russell
+ * @author Artem Bilan
+ *
  * @since 1.6
  *
  */
@@ -37,7 +39,7 @@ import org.springframework.context.annotation.Import;
 @Retention(RetentionPolicy.RUNTIME)
 @Documented
 @EnableRabbit
-@Import(RabbitListenerTestBootstrap.class)
+@Import(RabbitListenerTestSelector.class)
 public @interface RabbitListenerTest {
 
 	/**

spring-rabbit-test/src/main/java/org/springframework/amqp/rabbit/test/RabbitListenerTestBootstrap.java

@@ -16,36 +16,31 @@
 
 package org.springframework.amqp.rabbit.test;
 
-import org.springframework.amqp.rabbit.annotation.RabbitListenerAnnotationBeanPostProcessor;
 import org.springframework.amqp.rabbit.config.RabbitListenerConfigUtils;
-import org.springframework.beans.factory.config.BeanDefinition;
-import org.springframework.context.annotation.Bean;
+import org.springframework.beans.factory.support.BeanDefinitionBuilder;
+import org.springframework.beans.factory.support.BeanDefinitionRegistry;
 import org.springframework.context.annotation.Configuration;
-import org.springframework.context.annotation.ImportAware;
-import org.springframework.context.annotation.Role;
+import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
 import org.springframework.core.type.AnnotationMetadata;
 
 /**
  * Overrides the default BPP with a {@link RabbitListenerTestHarness}.
  *
  * @author Gary Russell
+ * @author Artem Bilan
+ *
  * @since 1.6
  *
  */
 @Configuration
-public class RabbitListenerTestBootstrap implements ImportAware {
-
-	private AnnotationMetadata importMetadata;
+public class RabbitListenerTestBootstrap implements ImportBeanDefinitionRegistrar {
 
 	@Override
-	public void setImportMetadata(AnnotationMetadata importMetadata) {
-		this.importMetadata = importMetadata;
-	}
-
-	@Bean(name = RabbitListenerConfigUtils.RABBIT_LISTENER_ANNOTATION_PROCESSOR_BEAN_NAME)
-	@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
-	public RabbitListenerAnnotationBeanPostProcessor rabbitListenerAnnotationProcessor() {
-		return new RabbitListenerTestHarness(this.importMetadata);
+	public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
+		registry.registerBeanDefinition(RabbitListenerConfigUtils.RABBIT_LISTENER_ANNOTATION_PROCESSOR_BEAN_NAME,
+				BeanDefinitionBuilder.rootBeanDefinition(RabbitListenerTestHarness.class)
+						.addConstructorArgValue(importingClassMetadata)
+						.getBeanDefinition());
 	}
 
 }

spring-rabbit-test/src/main/java/org/springframework/amqp/rabbit/test/RabbitListenerTestHarness.java

@@ -114,11 +114,6 @@ public class RabbitListenerTestHarness extends RabbitListenerAnnotationBeanPostP
 		return (T) this.listeners.get(id);
 	}
 
-	@Override
-	public int getOrder() {
-		return super.getOrder() - 100;
-	}
-
 	private static final class CaptureAdvice implements MethodInterceptor {
 
 		private final BlockingQueue<InvocationData> invocationData = new LinkedBlockingQueue<>();

spring-rabbit-test/src/main/java/org/springframework/amqp/rabbit/test/RabbitListenerTestSelector.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2019 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.amqp.rabbit.test;
+
+import org.springframework.amqp.rabbit.annotation.RabbitListenerConfigurationSelector;
+import org.springframework.core.Ordered;
+import org.springframework.core.annotation.Order;
+import org.springframework.core.type.AnnotationMetadata;
+
+/**
+ * A {@link RabbitListenerConfigurationSelector} extension to register
+ * a {@link RabbitListenerTestBootstrap}, but already with the higher order,
+ * so the {@link RabbitListenerTestHarness} bean is registered earlier,
+ * than {@link org.springframework.amqp.rabbit.annotation.RabbitListenerAnnotationBeanPostProcessor}.
+ *
+ * @author Artem Bilan
+ *
+ * @since 2.1.6
+ */
+@Order(Ordered.LOWEST_PRECEDENCE - 100)
+public class RabbitListenerTestSelector extends RabbitListenerConfigurationSelector {
+
+	@Override
+	public String[] selectImports(AnnotationMetadata importingClassMetadata) {
+		return new String[] { RabbitListenerTestBootstrap.class.getName() };
+	}
+
+}