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/mockmvc/EveryTestPreprocessing.java

@@ -0,0 +1,73 @@
+/*
+ * 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.mockmvc;
+
+import org.junit.Before;
+import org.junit.Rule;
+import org.springframework.restdocs.RestDocumentation;
+import org.springframework.restdocs.mockmvc.RestDocumentationResultHandler;
+import org.springframework.test.web.servlet.MockMvc;
+import org.springframework.test.web.servlet.setup.MockMvcBuilders;
+import org.springframework.web.context.WebApplicationContext;
+
+import static org.springframework.restdocs.hypermedia.HypermediaDocumentation.linkWithRel;
+import static org.springframework.restdocs.hypermedia.HypermediaDocumentation.links;
+import static org.springframework.restdocs.mockmvc.MockMvcRestDocumentation.document;
+import static org.springframework.restdocs.mockmvc.MockMvcRestDocumentation.documentationConfiguration;
+import static org.springframework.restdocs.mockmvc.RestDocumentationRequestBuilders.get;
+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.test.web.servlet.result.MockMvcResultMatchers.status;
+
+public class EveryTestPreprocessing {
+
+	@Rule
+	public final RestDocumentation restDocumentation = new RestDocumentation(
+			"target/generated-snippets");
+
+	private WebApplicationContext context;
+
+	// tag::setup[]
+	private MockMvc mockMvc;
+
+	private RestDocumentationResultHandler document;
+
+	@Before
+	public void setup() {
+		this.document = document("{method-name}", // <1>
+				preprocessRequest(removeHeaders("Foo")),
+				preprocessResponse(prettyPrint()));
+		this.mockMvc = MockMvcBuilders.webAppContextSetup(this.context)
+				.apply(documentationConfiguration(this.restDocumentation))
+				.alwaysDo(this.document) // <2>
+				.build();
+	}
+
+	// end::setup[]
+
+	public void use() throws Exception {
+		// tag::use[]
+		this.document.snippets( // <1>
+				links(linkWithRel("self").description("Canonical self link")));
+		this.mockMvc.perform(get("/")) // <2>
+				.andExpect(status().isOk());
+		// end::use[]
+	}
+
+}