Support RouterFunction in @EnableWebFlux

This commit removes the RouterFunctions.toHandlerMapping method, in
favor of native support for RouterFunctions in @EnableWebFlux
configuration classes.

In order to accomplish this, the HandlerStrategies components has been
repurposed to only be used for the "bare-bones" HttpHandler, while the
(newly introduced) RouterFunctionMapping uses the strategies as exposed
through WebFluxConfigurationSupport.

Furthermore, this commit also introduces support for testing
RouterFunctions without resorting to an application context.

Issue: SPR-15536

spring-test/src/main/java/org/springframework/test/web/reactive/server/DefaultRouterFunctionSpec.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2002-2017 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.test.web.reactive.server;
+
+import org.springframework.web.reactive.function.server.HandlerStrategies;
+import org.springframework.web.reactive.function.server.RouterFunction;
+import org.springframework.web.reactive.function.server.RouterFunctions;
+import org.springframework.web.server.WebHandler;
+import org.springframework.web.server.adapter.WebHttpHandlerBuilder;
+
+/**
+ * Spec for setting up server-less testing against a RouterFunction.
+ *
+ * @author Arjen Poutsma
+ * @since 5.0
+ */
+class DefaultRouterFunctionSpec extends AbstractMockServerSpec<WebTestClient.RouterFunctionSpec>
+		implements WebTestClient.RouterFunctionSpec {
+
+	private final RouterFunction<?> routerFunction;
+
+	private HandlerStrategies handlerStrategies = HandlerStrategies.withDefaults();
+
+
+	DefaultRouterFunctionSpec(RouterFunction<?> routerFunction) {
+		this.routerFunction = routerFunction;
+	}
+
+
+	@Override
+	public WebTestClient.RouterFunctionSpec handlerStrategies(HandlerStrategies handlerStrategies) {
+		if (handlerStrategies != null) {
+			this.handlerStrategies = handlerStrategies;
+		}
+		return this;
+	}
+
+	@Override
+	protected WebHttpHandlerBuilder initHttpHandlerBuilder() {
+		WebHandler webHandler = RouterFunctions.toWebHandler(this.routerFunction, this.handlerStrategies);
+		return WebHttpHandlerBuilder.webHandler(webHandler);
+	}
+
+}

spring-test/src/main/java/org/springframework/test/web/reactive/server/RouterFunctionSpec.java

@@ -1,62 +0,0 @@
-/*
- * Copyright 2002-2017 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.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.springframework.test.web.reactive.server;
-
-import org.springframework.context.ApplicationContext;
-import org.springframework.context.annotation.AnnotationConfigApplicationContext;
-import org.springframework.web.reactive.DispatcherHandler;
-import org.springframework.web.reactive.HandlerAdapter;
-import org.springframework.web.reactive.HandlerMapping;
-import org.springframework.web.reactive.HandlerResultHandler;
-import org.springframework.web.reactive.function.server.RouterFunction;
-import org.springframework.web.reactive.function.server.RouterFunctions;
-import org.springframework.web.reactive.function.server.support.HandlerFunctionAdapter;
-import org.springframework.web.reactive.function.server.support.ServerResponseResultHandler;
-import org.springframework.web.server.adapter.WebHttpHandlerBuilder;
-
-/**
- * Spec for setting up server-less testing against a RouterFunction.
- *
- * @author Rossen Stoyanchev
- * @since 5.0
- */
-public class RouterFunctionSpec extends AbstractMockServerSpec<RouterFunctionSpec> {
-
-	private final RouterFunction<?> routerFunction;
-
-
-	RouterFunctionSpec(RouterFunction<?> routerFunction) {
-		this.routerFunction = routerFunction;
-	}
-
-
-	@Override
-	protected WebHttpHandlerBuilder initHttpHandlerBuilder() {
-		return WebHttpHandlerBuilder.applicationContext(initApplicationContext());
-	}
-
-	private ApplicationContext initApplicationContext() {
-		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
-		context.registerBean("webHandler", DispatcherHandler.class, () -> new DispatcherHandler());
-		context.registerBean(HandlerMapping.class, () -> RouterFunctions.toHandlerMapping(this.routerFunction));
-		context.registerBean(HandlerAdapter.class, () -> new HandlerFunctionAdapter());
-		context.registerBean(HandlerResultHandler.class, () -> new ServerResponseResultHandler());
-		context.refresh();
-		return context;
-	}
-
-}

spring-test/src/main/java/org/springframework/test/web/reactive/server/WebTestClient.java

@@ -48,6 +48,7 @@ import org.springframework.web.reactive.function.client.ExchangeFilterFunction;
 import org.springframework.web.reactive.function.client.ExchangeFunction;
 import org.springframework.web.reactive.function.client.ExchangeStrategies;
 import org.springframework.web.reactive.function.client.WebClient;
+import org.springframework.web.reactive.function.server.HandlerStrategies;
 import org.springframework.web.reactive.function.server.RouterFunction;
 import org.springframework.web.reactive.result.method.annotation.ArgumentResolverConfigurer;
 import org.springframework.web.server.ServerWebExchange;
@@ -169,8 +170,8 @@ public interface WebTestClient {
 	 * @param routerFunction the RouterFunction to test
 	 * @return the {@link WebTestClient} builder
 	 */
-	static MockServerSpec<?> bindToRouterFunction(RouterFunction<?> routerFunction) {
-		return new RouterFunctionSpec(routerFunction);
+	static RouterFunctionSpec bindToRouterFunction(RouterFunction<?> routerFunction) {
+		return new DefaultRouterFunctionSpec(routerFunction);
 	}
 
 	/**
@@ -285,6 +286,18 @@ public interface WebTestClient {
 
 	}
 
+	/**
+	 * Specification for customizing router function configuration.
+	 */
+	interface RouterFunctionSpec extends MockServerSpec<RouterFunctionSpec> {
+
+		/**
+		 * Configure handler strategies.
+		 */
+		RouterFunctionSpec handlerStrategies(HandlerStrategies handlerStrategies);
+
+	}
+
 	/**
 	 * Steps for customizing the {@link WebClient} used to test with
 	 * internally delegating to a {@link WebClient.Builder}.