Polish

Fixes gh-16014

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/metrics/web/servlet/WebMvcMetricsFilterTests.java

 /*
- * Copyright 2012-2018 the original author or authors.
+ * Copyright 2012-2019 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.
@@ -76,6 +76,7 @@ import org.springframework.web.context.WebApplicationContext;
 import org.springframework.web.filter.OncePerRequestFilter;
 import org.springframework.web.servlet.ModelAndView;
 import org.springframework.web.servlet.config.annotation.EnableWebMvc;
+import org.springframework.web.servlet.mvc.method.annotation.ResponseBodyEmitter;
 import org.springframework.web.util.NestedServletException;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -188,6 +189,16 @@ public class WebMvcMetricsFilterTests {
 				.tags("exception", "RuntimeException").timer().count()).isEqualTo(1L);
 	}
 
+	@Test
+	public void streamingError() throws Exception {
+		MvcResult result = this.mvc.perform(get("/api/c1/streamingError"))
+				.andExpect(request().asyncStarted()).andReturn();
+		assertThatCode(
+				() -> this.mvc.perform(asyncDispatch(result)).andExpect(status().isOk()));
+		assertThat(this.registry.get("http.server.requests")
+				.tags("exception", "IOException").timer().count()).isEqualTo(1L);
+	}
+
 	@Test
 	public void anonymousError() {
 		try {
@@ -451,6 +462,14 @@ public class WebMvcMetricsFilterTests {
 			throw new RuntimeException("Boom on " + id + "!");
 		}
 
+		@GetMapping("/streamingError")
+		public ResponseBodyEmitter streamingError() {
+			ResponseBodyEmitter emitter = new ResponseBodyEmitter();
+			emitter.completeWithError(
+					new IOException("error while writing to the response"));
+			return emitter;
+		}
+
 		@Timed
 		@GetMapping("/regex/{id:\\.[a-z]+}")
 		public String successfulRegex(@PathVariable String id) {