Merge pull request #44259 from nosan

* pr/44259:
  Polish "Do not auto-configure ViewResolver if spring-webmvc is absent"
  Do not auto-configure ViewResolver if spring-webmvc is absent

Closes gh-44259

Author: snicoll

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/thymeleaf/ThymeleafAutoConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -56,6 +56,7 @@
 import org.springframework.util.MimeType;
 import org.springframework.util.unit.DataSize;
 import org.springframework.web.servlet.resource.ResourceUrlEncodingFilter;
+import org.springframework.web.servlet.view.AbstractCachingViewResolver;
 
 /**
  * {@link EnableAutoConfiguration Auto-configuration} for Thymeleaf.
@@ -142,6 +143,7 @@ FilterRegistrationBean<ResourceUrlEncodingFilter> resourceUrlEncodingFilter() {
 		}
 
 		@Configuration(proxyBeanMethods = false)
+		@ConditionalOnClass(AbstractCachingViewResolver.class)
 		static class ThymeleafViewResolverConfiguration {
 
 			@Bean

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/thymeleaf/ThymeleafServletAutoConfigurationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -60,6 +60,7 @@
 import org.springframework.web.servlet.ViewResolver;
 import org.springframework.web.servlet.resource.ResourceUrlEncodingFilter;
 import org.springframework.web.servlet.support.RequestContext;
+import org.springframework.web.servlet.view.AbstractCachingViewResolver;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -336,6 +337,12 @@ void cachingCanBeDisabled() {
 		});
 	}
 
+	@Test
+	void missingAbstractCachingViewResolver() {
+		this.contextRunner.withClassLoader(new FilteredClassLoader(AbstractCachingViewResolver.class))
+			.run((context) -> assertThat(context).hasNotFailed().doesNotHaveBean("thymeleafViewResolver"));
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class LayoutDialectConfiguration {