@EnableWebFlux setup supports WebSocketHandler

Closes gh-22587

spring-webflux/src/test/java/org/springframework/web/reactive/config/DelegatingWebFluxConfigurationTests.java

@@ -37,11 +37,14 @@ import org.springframework.validation.Validator;
 import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;
 import org.springframework.web.bind.support.ConfigurableWebBindingInitializer;
 import org.springframework.web.reactive.accept.RequestedContentTypeResolverBuilder;
+import org.springframework.web.reactive.socket.server.WebSocketService;
+import org.springframework.web.reactive.socket.server.support.WebSocketHandlerAdapter;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.BDDMockito.given;
 import static org.mockito.BDDMockito.willAnswer;
+import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
 
 /**
@@ -73,6 +76,7 @@ public class DelegatingWebFluxConfigurationTests {
 		delegatingConfig.setApplicationContext(new StaticApplicationContext());
 		given(webFluxConfigurer.getValidator()).willReturn(null);
 		given(webFluxConfigurer.getMessageCodesResolver()).willReturn(null);
+		given(webFluxConfigurer.getWebSocketService()).willReturn(null);
 	}
 
 
@@ -125,6 +129,17 @@ public class DelegatingWebFluxConfigurationTests {
 		verify(webFluxConfigurer).configurePathMatching(any(PathMatchConfigurer.class));
 	}
 
+	@Test
+	void webSocketService() {
+		WebSocketService service = mock(WebSocketService.class);
+		given(webFluxConfigurer.getWebSocketService()).willReturn(service);
+
+		delegatingConfig.setConfigurers(Collections.singletonList(webFluxConfigurer));
+		WebSocketHandlerAdapter adapter = delegatingConfig.webFluxWebSocketHandlerAdapter();
+
+		assertThat(adapter.getWebSocketService()).isSameAs(service);
+	}
+
 	@Test
 	public void responseBodyResultHandler() {
 		delegatingConfig.setConfigurers(Collections.singletonList(webFluxConfigurer));