Fix request parameters in curl snippet for multipart requests

Previously, request parameters would be provided via -d. This is
incorrect for a multipart request that is also using -F. This commit
updates the generation of the curl request snippet to use -F for request
parameters when the request is a multipart request.

Closes gh-93

spring-restdocs/src/main/java/org/springframework/restdocs/curl/CurlDocumentation.java

@@ -176,6 +176,14 @@ public abstract class CurlDocumentation {
 				this.writer
 						.print(String.format(" -d '%s'", request.getContentAsString()));
 			}
+			else if (request.isMultipartRequest()) {
+				for (Entry<String, String[]> entry : request.getParameterMap().entrySet()) {
+					for (String value : entry.getValue()) {
+						this.writer.print(String.format(" -F '%s=%s'", entry.getKey(),
+								value));
+					}
+				}
+			}
 			else if (request.isPostRequest() || request.isPutRequest()) {
 				String queryString = request.getParameterMapAsQueryString();
 				if (StringUtils.hasText(queryString)) {

spring-restdocs/src/main/java/org/springframework/restdocs/util/DocumentableHttpServletRequest.java

@@ -230,6 +230,15 @@ public class DocumentableHttpServletRequest {
 		return this.delegate.getContextPath();
 	}
 
+	/**
+	 * Returns a map of the request's parameters
+	 * @return The map of parameters
+	 * @see HttpServletRequest#getParameterMap()
+	 */
+	public Map<String, String[]> getParameterMap() {
+		return this.delegate.getParameterMap();
+	}
+
 	private String getQueryString() {
 		if (this.delegate.getQueryString() != null) {
 			return this.delegate.getQueryString();

spring-restdocs/src/test/java/org/springframework/restdocs/curl/CurlDocumentationTests.java

@@ -287,4 +287,19 @@ public class CurlDocumentationTests {
 				result(fileUpload("/upload").file(multipartFile)));
 	}
 
+	@Test
+	public void multipartPostWithParameters() throws IOException {
+		String expectedContent = "$ curl 'http://localhost/upload' -i -X POST -H "
+				+ "'Content-Type: multipart/form-data' -F "
+				+ "'image=@documents/images/example.png' -F 'a=apple' -F 'a=avocado' "
+				+ "-F 'b=banana'";
+		this.snippet.expectCurlRequest("multipart-post").withContents(
+				codeBlock("bash").content(expectedContent));
+		MockMultipartFile multipartFile = new MockMultipartFile("image",
+				"documents/images/example.png", null, "bytes".getBytes());
+		documentCurlRequest("multipart-post").handle(
+				result(fileUpload("/upload").file(multipartFile)
+						.param("a", "apple", "avocado").param("b", "banana")));
+	}
+
 }