Add additional test for reactive security auto-config

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/security/reactive/ReactiveSecurityAutoConfigurationTests.java

@@ -17,12 +17,16 @@
 package org.springframework.boot.autoconfigure.security.reactive;
 
 import org.junit.jupiter.api.Test;
+import reactor.core.publisher.Flux;
 
 import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.test.context.FilteredClassLoader;
 import org.springframework.boot.test.context.runner.ReactiveWebApplicationContextRunner;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.security.config.annotation.web.reactive.EnableWebFluxSecurity;
 import org.springframework.security.web.server.WebFilterChainProxy;
+import org.springframework.web.reactive.config.WebFluxConfigurer;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.Mockito.mock;
@@ -51,6 +55,16 @@ class ReactiveSecurityAutoConfigurationTests {
 				.run((context) -> assertThat(context).getBean(WebFilterChainProxy.class).isNotNull());
 	}
 
+	@Test
+	void autoConfigurationIsConditionalOnClass() {
+		this.contextRunner
+				.withClassLoader(new FilteredClassLoader(Flux.class, EnableWebFluxSecurity.class,
+						WebFilterChainProxy.class, WebFluxConfigurer.class))
+				.withConfiguration(AutoConfigurations.of(ReactiveSecurityAutoConfiguration.class,
+						ReactiveUserDetailsServiceAutoConfiguration.class))
+				.run((context) -> assertThat(context).doesNotHaveBean(WebFilterChainProxy.class));
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	static class WebFilterChainProxyConfiguration {