Test fix in gh-22638

spring-webmvc/src/test/java/org/springframework/web/servlet/mvc/method/annotation/RequestMappingHandlerAdapterTests.java

 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -17,6 +17,7 @@
 package org.springframework.web.servlet.mvc.method.annotation;
 
 import java.lang.reflect.Method;
+import java.lang.reflect.Type;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -29,15 +30,18 @@ import org.junit.BeforeClass;
 import org.junit.Test;
 
 import org.springframework.core.MethodParameter;
+import org.springframework.http.HttpInputMessage;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
 import org.springframework.http.ResponseEntity;
 import org.springframework.http.converter.HttpMessageConverter;
+import org.springframework.http.converter.StringHttpMessageConverter;
 import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
 import org.springframework.http.converter.json.MappingJacksonValue;
 import org.springframework.http.server.ServerHttpRequest;
 import org.springframework.http.server.ServerHttpResponse;
 import org.springframework.http.server.ServletServerHttpResponse;
+import org.springframework.lang.Nullable;
 import org.springframework.mock.web.test.MockHttpServletRequest;
 import org.springframework.mock.web.test.MockHttpServletResponse;
 import org.springframework.ui.Model;
@@ -60,6 +64,7 @@ import static org.junit.Assert.*;
  * Unit tests for {@link RequestMappingHandlerAdapter}.
  *
  * @author Rossen Stoyanchev
+ * @author Sam Brannen
  * @see ServletAnnotationControllerHandlerMethodTests
  * @see HandlerMethodAnnotationDetectionTests
  * @see RequestMappingHandlerAdapterIntegrationTests
@@ -342,8 +347,15 @@ public class RequestMappingHandlerAdapterTests {
 		}
 	}
 
+	/**
+	 * This class additionally implements {@link RequestBodyAdvice} solely for the purpose
+	 * of verifying that controller advice implementing both {@link ResponseBodyAdvice}
+	 * and {@link RequestBodyAdvice} does not get registered twice.
+	 *
+	 * @see <a href="https://github.com/spring-projects/spring-framework/pull/22638">gh-22638</a>
+	 */
 	@ControllerAdvice
-	private static class ResponseCodeSuppressingAdvice extends AbstractMappingJacksonResponseBodyAdvice {
+	private static class ResponseCodeSuppressingAdvice extends AbstractMappingJacksonResponseBodyAdvice implements RequestBodyAdvice {
 
 		@Override
 		protected void beforeBodyWriteInternal(MappingJacksonValue bodyContainer, MediaType contentType,
@@ -357,6 +369,35 @@ public class RequestMappingHandlerAdapterTests {
 			map.put("message", bodyContainer.getValue());
 			bodyContainer.setValue(map);
 		}
+
+		@Override
+		public boolean supports(MethodParameter methodParameter, Type targetType,
+				Class<? extends HttpMessageConverter<?>> converterType) {
+
+			return StringHttpMessageConverter.class.equals(converterType);
+		}
+
+		@Override
+		public HttpInputMessage beforeBodyRead(HttpInputMessage inputMessage, MethodParameter parameter,
+				Type targetType, Class<? extends HttpMessageConverter<?>> converterType) {
+
+			return inputMessage;
+		}
+
+		@Override
+		public Object afterBodyRead(Object body, HttpInputMessage inputMessage, MethodParameter parameter,
+				Type targetType, Class<? extends HttpMessageConverter<?>> converterType) {
+
+			return body;
+		}
+
+		@Override
+		public Object handleEmptyBody(@Nullable Object body, HttpInputMessage inputMessage, MethodParameter parameter,
+				Type targetType, Class<? extends HttpMessageConverter<?>> converterType) {
+
+			return "default value for empty body";
+		}
+
 	}
 
 }