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

Closes gh-384

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

@@ -0,0 +1,57 @@
+/*
+ * 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.test.web.reactive.server.WebTestClient;
+import org.springframework.util.LinkedMultiValueMap;
+import org.springframework.util.MultiValueMap;
+import org.springframework.web.reactive.function.BodyInserters;
+
+import static org.springframework.restdocs.request.RequestDocumentation.parameterWithName;
+import static org.springframework.restdocs.request.RequestDocumentation.requestParameters;
+import static org.springframework.restdocs.webtestclient.WebTestClientRestDocumentation.document;
+
+public class RequestParameters {
+
+	// @formatter:off
+
+	private WebTestClient webTestClient;
+
+	public void getQueryStringSnippet() throws Exception {
+		// tag::request-parameters-query-string[]
+		this.webTestClient.get().uri("/users?page=2&per_page=100") // <1>
+			.exchange().expectStatus().isOk().expectBody()
+			.consumeWith(document("users", requestParameters( // <2>
+					parameterWithName("page").description("The page to retrieve"), // <3>
+					parameterWithName("per_page").description("Entries per page") // <4>
+			)));
+		// end::request-parameters-query-string[]
+	}
+
+	public void postFormDataSnippet() throws Exception {
+		// tag::request-parameters-form-data[]
+		MultiValueMap<String, String> formData = new LinkedMultiValueMap<>();
+		formData.add("username", "Tester");
+		this.webTestClient.post().uri("/users").body(BodyInserters.fromFormData(formData)) // <1>
+			.exchange().expectStatus().isCreated().expectBody()
+			.consumeWith(document("create-user", requestParameters(
+				parameterWithName("username").description("The user's username")
+		)));
+		// end::request-parameters-form-data[]
+	}
+
+}