Add DefaultHandlerExceptionResolver to child context

Fixes gh-14084

Author: mbhave

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/autoconfigure/EndpointWebMvcChildContextConfiguration.java

@@ -65,6 +65,7 @@
 import org.springframework.web.servlet.HandlerMapping;
 import org.springframework.web.servlet.ModelAndView;
 import org.springframework.web.servlet.config.annotation.EnableWebMvc;
+import org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver;
 
 /**
  * Configuration triggered from {@link EndpointWebMvcAutoConfiguration} when a new
@@ -317,6 +318,9 @@ private List<HandlerExceptionResolver> extractResolvers() {
 					.values());
 			list.remove(this);
 			AnnotationAwareOrderComparator.sort(list);
+			if (list.isEmpty()) {
+				list.add(new DefaultHandlerExceptionResolver());
+			}
 			return list;
 		}
 

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/autoconfigure/EndpointWebMvcChildContextConfigurationTests.java

@@ -0,0 +1,125 @@
+/*
+ * 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://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.boot.actuate.autoconfigure;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Import;
+import org.springframework.mock.web.MockHttpServletRequest;
+import org.springframework.mock.web.MockHttpServletResponse;
+import org.springframework.mock.web.MockServletContext;
+import org.springframework.web.HttpRequestMethodNotSupportedException;
+import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
+import org.springframework.web.servlet.HandlerExceptionResolver;
+import org.springframework.web.servlet.ModelAndView;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link EndpointWebMvcChildContextConfiguration}.
+ *
+ * @author Madhura Bhave
+ */
+public class EndpointWebMvcChildContextConfigurationTests {
+
+	private AnnotationConfigWebApplicationContext context;
+
+	private MockHttpServletRequest request = new MockHttpServletRequest();
+
+	private MockHttpServletResponse response = new MockHttpServletResponse();
+
+	@Before
+	public void setup() {
+		this.context = new AnnotationConfigWebApplicationContext();
+		this.context.setServletContext(new MockServletContext());
+	}
+
+	@After
+	public void close() {
+		if (this.context != null) {
+			this.context.close();
+		}
+	}
+
+	@Test
+	public void compositeResolverShouldAddDefaultResolverIfNonePresent() {
+		this.context.register(BaseConfiguration.class);
+		this.context.setParent(getParentApplicationContext());
+		this.context.refresh();
+		EndpointWebMvcChildContextConfiguration.CompositeHandlerExceptionResolver resolver = this.context
+				.getBean(
+						EndpointWebMvcChildContextConfiguration.CompositeHandlerExceptionResolver.class);
+		ModelAndView resolved = resolver.resolveException(this.request, this.response,
+				null, new HttpRequestMethodNotSupportedException("POST"));
+		assertThat(resolved).isNotNull();
+	}
+
+	@Test
+	public void compositeResolverShouldDelegateToOtherResolversInContext() {
+		this.context.register(HandlerExceptionResolverConfiguration.class);
+		this.context.setParent(getParentApplicationContext());
+		this.context.refresh();
+		EndpointWebMvcChildContextConfiguration.CompositeHandlerExceptionResolver resolver = this.context
+				.getBean(
+						EndpointWebMvcChildContextConfiguration.CompositeHandlerExceptionResolver.class);
+		ModelAndView resolved = resolver.resolveException(this.request, this.response,
+				null, new HttpRequestMethodNotSupportedException("POST"));
+		assertThat(resolved.getViewName()).isEqualTo("test-view");
+	}
+
+	private AnnotationConfigWebApplicationContext getParentApplicationContext() {
+		AnnotationConfigWebApplicationContext parent = new AnnotationConfigWebApplicationContext();
+		parent.refresh();
+		return parent;
+	}
+
+	@Configuration
+	@Import(EndpointWebMvcChildContextConfiguration.class)
+	@EnableConfigurationProperties(ManagementServerProperties.class)
+	static class BaseConfiguration {
+
+	}
+
+	@Configuration
+	@Import(BaseConfiguration.class)
+	static class HandlerExceptionResolverConfiguration {
+
+		@Bean
+		public HandlerExceptionResolver testResolver() {
+			return new TestHandlerExceptionResolver();
+		}
+
+	}
+
+	static class TestHandlerExceptionResolver implements HandlerExceptionResolver {
+
+		@Override
+		public ModelAndView resolveException(HttpServletRequest request,
+				HttpServletResponse response, Object handler, Exception ex) {
+			return new ModelAndView("test-view");
+		}
+
+	}
+
+}