From c82a9be5d577223bdd57407667184362bcc5e404 Mon Sep 17 00:00:00 2001
From: Marcin Grzejszczak <marcin.grzejszczak@gmail.com>
Date: Tue, 1 Dec 2020 13:44:12 +0100
Subject: [PATCH] Added conditional on class for web auto configuration; fixes
 gh-1790

---
 .../web/TraceWebServletAutoConfiguration.java    |  2 ++
 .../TraceWebServletAutoConfigurationTests.java   | 16 ++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/web/TraceWebServletAutoConfiguration.java b/spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/web/TraceWebServletAutoConfiguration.java
index f5a71efba..b919a5398 100644
--- a/spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/web/TraceWebServletAutoConfiguration.java
+++ b/spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/web/TraceWebServletAutoConfiguration.java
@@ -44,6 +44,7 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
 import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
+import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;
 
 /**
  * {@link org.springframework.boot.autoconfigure.EnableAutoConfiguration
@@ -61,6 +62,7 @@ import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
 @ConditionalOnWebApplication(type = ConditionalOnWebApplication.Type.SERVLET)
 @ConditionalOnBean(HttpTracing.class)
 @AutoConfigureAfter(TraceHttpAutoConfiguration.class)
+@ConditionalOnClass(HandlerInterceptorAdapter.class)
 @Import(SpanCustomizingAsyncHandlerInterceptor.class)
 public class TraceWebServletAutoConfiguration {
 
diff --git a/tests/spring-cloud-sleuth-instrumentation-mvc-tests/src/test/java/org/springframework/cloud/sleuth/instrument/web/TraceWebServletAutoConfigurationTests.java b/tests/spring-cloud-sleuth-instrumentation-mvc-tests/src/test/java/org/springframework/cloud/sleuth/instrument/web/TraceWebServletAutoConfigurationTests.java
index 9bf7035bb..8a25f550a 100644
--- a/tests/spring-cloud-sleuth-instrumentation-mvc-tests/src/test/java/org/springframework/cloud/sleuth/instrument/web/TraceWebServletAutoConfigurationTests.java
+++ b/tests/spring-cloud-sleuth-instrumentation-mvc-tests/src/test/java/org/springframework/cloud/sleuth/instrument/web/TraceWebServletAutoConfigurationTests.java
@@ -19,8 +19,10 @@ package org.springframework.cloud.sleuth.instrument.web;
 import org.junit.Test;
 
 import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.test.context.FilteredClassLoader;
 import org.springframework.boot.test.context.runner.WebApplicationContextRunner;
 import org.springframework.cloud.sleuth.autoconfig.TraceAutoConfiguration;
+import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -36,6 +38,20 @@ public class TraceWebServletAutoConfigurationTests {
 					TraceHttpAutoConfiguration.class, TraceWebAutoConfiguration.class,
 					TraceWebServletAutoConfiguration.class));
 
+	@Test
+	public void shouldNotCreateTracedWebBeansWhenServletClassMissing() {
+		this.contextRunner.withClassLoader(new FilteredClassLoader(HandlerInterceptorAdapter.class)).run((context) -> {
+			assertThat(context).doesNotHaveBean(TraceWebAspect.class);
+		});
+	}
+
+	@Test
+	public void shouldCreateTracedWebBeansWhenServletClassNotMissing() {
+		this.contextRunner.run((context) -> {
+			assertThat(context).hasSingleBean(TraceWebAspect.class);
+		});
+	}
+
 	@Test
 	public void shouldNotCreateExceptionLoggingFilterBeanByDefault() {
 		this.contextRunner.run((context) -> {