Add support for using WebFlux's WebTestClient to document an API

Closes gh-384

docs/src/test/java/com/example/webtestclient/InvokeService.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2014-2017 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 com.example.webtestclient;
+
+import org.springframework.http.MediaType;
+import org.springframework.test.web.reactive.server.WebTestClient;
+
+import static org.springframework.restdocs.webtestclient.WebTestClientRestDocumentation.document;
+
+public class InvokeService {
+
+	private WebTestClient webTestClient;
+
+	public void invokeService() throws Exception {
+		// tag::invoke-service[]
+		this.webTestClient.get().uri("/").accept(MediaType.APPLICATION_JSON) // <1>
+				.exchange().expectStatus().isOk() // <2>
+				.expectBody().consumeWith(document("index")); // <3>
+		// end::invoke-service[]
+	}
+
+}