Add support for using REST Assured to generate documentation snippets

This commit adds a new module, spring-restdocs-restassured, that
can be used to generate documentation snippets when testing a service
with REST Assured.

Please refer to the updated reference documentation for details.

Thanks to Johan Haleby for making a change to REST Assured so that
path parameters could be documented.

Closes gh-102

docs/src/test/java/com/example/restassured/EveryTestPreprocessing.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2014-2016 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.restassured;
+
+import org.junit.Before;
+import org.junit.Rule;
+import org.springframework.restdocs.RestDocumentation;
+import org.springframework.restdocs.restassured.RestDocumentationFilter;
+
+import com.jayway.restassured.RestAssured;
+import com.jayway.restassured.builder.RequestSpecBuilder;
+import com.jayway.restassured.specification.RequestSpecification;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.springframework.restdocs.hypermedia.HypermediaDocumentation.linkWithRel;
+import static org.springframework.restdocs.hypermedia.HypermediaDocumentation.links;
+import static org.springframework.restdocs.operation.preprocess.Preprocessors.preprocessRequest;
+import static org.springframework.restdocs.operation.preprocess.Preprocessors.preprocessResponse;
+import static org.springframework.restdocs.operation.preprocess.Preprocessors.prettyPrint;
+import static org.springframework.restdocs.operation.preprocess.Preprocessors.removeHeaders;
+import static org.springframework.restdocs.restassured.RestAssuredRestDocumentation.document;
+import static org.springframework.restdocs.restassured.RestAssuredRestDocumentation.documentationConfiguration;
+
+public class EveryTestPreprocessing {
+
+	@Rule
+	public final RestDocumentation restDocumentation = new RestDocumentation(
+			"target/generated-snippets");
+
+	// tag::setup[]
+	private RequestSpecification spec;
+
+	private RestDocumentationFilter document;
+
+	@Before
+	public void setup() {
+		this.document = document("{method-name}",
+				preprocessRequest(removeHeaders("Foo")),
+				preprocessResponse(prettyPrint())); // <1>
+		this.spec = new RequestSpecBuilder()
+				.addFilter(documentationConfiguration(this.restDocumentation))
+				.addFilter(this.document)// <2>
+				.build();
+	}
+
+	// end::setup[]
+
+	public void use() throws Exception {
+		// tag::use[]
+		this.document.snippets( // <1>
+				links(linkWithRel("self").description("Canonical self link")));
+		RestAssured.given(this.spec) // <2>
+			.when().get("/")
+			.then().assertThat().statusCode(is(200));
+		// end::use[]
+	}
+
+}