BAEL-878 [2] (#2194)

* code snippets for the `Java 9 Stream API improvements` article

* code snippets for the `Java 9 Stream API improvements` article [2 attempt]

* removed the first attempt

* the Spring 5 WebClient

* delted stream features test

* HttpMediaTypeNotAcceptableExceptionExampleController [0]

* reactive web client service was removed

* new WebClient

* new WebClient [2]

spring-5/src/test/java/com/baeldung/web/client/WebTestClientTest.java

@@ -0,0 +1,58 @@
+package com.baeldung.web.client;
+
+import com.baeldung.Spring5Application;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.web.server.LocalServerPort;
+import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.test.web.reactive.server.WebTestClient;
+import org.springframework.web.reactive.function.server.RequestPredicates;
+import org.springframework.web.reactive.function.server.RouterFunction;
+import org.springframework.web.reactive.function.server.RouterFunctions;
+import org.springframework.web.reactive.function.server.ServerResponse;
+import org.springframework.web.server.WebHandler;
+import reactor.core.publisher.Mono;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest(classes = Spring5Application.class, webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
+public class WebTestClientTest {
+
+    @LocalServerPort
+    private int port;
+
+    private final RouterFunction ROUTER_FUNCTION = RouterFunctions.route(
+            RequestPredicates.GET("/resource"),
+            request -> ServerResponse.ok().build()
+    );
+    private final WebHandler WEB_HANDLER = exchange -> Mono.empty();
+
+    @Test
+    public void testWebTestClientWithServerWebHandler() {
+        WebTestClient.bindToWebHandler(WEB_HANDLER).build();
+    }
+
+    @Test
+    public void testWebTestClientWithRouterFunction() {
+        WebTestClient
+                .bindToRouterFunction(ROUTER_FUNCTION)
+                .build().get().uri("/resource")
+                .exchange()
+                .expectStatus().isOk()
+                .expectBody().isEmpty();
+    }
+
+    @Test
+    public void testWebTestClientWithServerURL() {
+        WebTestClient
+                .bindToServer()
+                .baseUrl("http://localhost:" + port)
+                .build()
+                .get()
+                .uri("/resource")
+                .exchange()
+                .expectStatus().is4xxClientError()
+                .expectBody();
+    }
+
+}