Add DefaultHandlerExceptionResolver to child context

Fixes gh-10560

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/web/servlet/CompositeHandlerExceptionResolver.java

@@ -28,6 +28,7 @@ import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.core.annotation.AnnotationAwareOrderComparator;
 import org.springframework.web.servlet.HandlerExceptionResolver;
 import org.springframework.web.servlet.ModelAndView;
+import org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver;
 
 /**
  * Composite {@link HandlerExceptionResolver}.
@@ -60,6 +61,9 @@ class CompositeHandlerExceptionResolver implements HandlerExceptionResolver {
 				this.beanFactory.getBeansOfType(HandlerExceptionResolver.class).values());
 		list.remove(this);
 		AnnotationAwareOrderComparator.sort(list);
+		if (list.isEmpty()) {
+			list.add(new DefaultHandlerExceptionResolver());
+		}
 		return list;
 	}
 

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/web/servlet/CompositeHandlerExceptionResolverTests.java

@@ -0,0 +1,103 @@
+/*
+ * Copyright 2012-2017 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.web.servlet;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import org.junit.Test;
+
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+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.web.HttpRequestMethodNotSupportedException;
+import org.springframework.web.servlet.DispatcherServlet;
+import org.springframework.web.servlet.HandlerExceptionResolver;
+import org.springframework.web.servlet.ModelAndView;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link CompositeHandlerExceptionResolver}.
+ *
+ * @author Madhura Bhave
+ */
+public class CompositeHandlerExceptionResolverTests {
+
+	private AnnotationConfigApplicationContext context;
+
+	private MockHttpServletRequest request = new MockHttpServletRequest();
+
+	private MockHttpServletResponse response = new MockHttpServletResponse();
+
+	@Test
+	public void resolverShouldDelegateToOtherResolversInContext() throws Exception {
+		load(TestConfiguration.class);
+		CompositeHandlerExceptionResolver resolver = (CompositeHandlerExceptionResolver) this.context.getBean(DispatcherServlet.HANDLER_EXCEPTION_RESOLVER_BEAN_NAME);
+		ModelAndView resolved = resolver.resolveException(this.request, this.response, null, new HttpRequestMethodNotSupportedException("POST"));
+		assertThat(resolved.getViewName()).isEqualTo("test-view");
+	}
+
+	@Test
+	public void resolverShouldAddDefaultResolverIfNonePresent() throws Exception {
+		load(BaseConfiguration.class);
+		CompositeHandlerExceptionResolver resolver = (CompositeHandlerExceptionResolver) this.context.getBean(DispatcherServlet.HANDLER_EXCEPTION_RESOLVER_BEAN_NAME);
+		ModelAndView resolved = resolver.resolveException(this.request, this.response, null, new HttpRequestMethodNotSupportedException("POST"));
+		assertThat(resolved).isNotNull();
+	}
+
+	private void load(Class<?>... configs) {
+		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
+		context.register(configs);
+		context.refresh();
+		this.context = context;
+	}
+
+	@Configuration
+	static class BaseConfiguration {
+
+		@Bean(name = DispatcherServlet.HANDLER_EXCEPTION_RESOLVER_BEAN_NAME)
+		public CompositeHandlerExceptionResolver compositeHandlerExceptionResolver() {
+			return new CompositeHandlerExceptionResolver();
+		}
+
+	}
+
+	@Configuration
+	@Import(BaseConfiguration.class)
+	static class TestConfiguration {
+
+		@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");
+		}
+
+	}
+
+}