Improve handling of the Content-Length header

Previously, some MockMvc-specific logic would add a Content-Length
header to every request that had content. This led to the curl request
snippet containing a -H option for the Content-Length header. This is
unnecessary as curl will automatically generate a Content-Length
header based on the data that's being sent to the server. A secondary
problem was the inconsistent automatic addition of a Content-Length
header; the header was not automatically added to responses.

This commit remove the MockMvc-specific logic in favour of some new
logic in the core project to automatically add a Content-Length header
to both requests and responses. The curl request snippet has been
updated to supress the header in favour of curl's automatic
generation.

Closes gh-111

spring-restdocs-core/src/main/java/org/springframework/restdocs/curl/CurlRequestSnippet.java

@@ -115,8 +115,10 @@ public class CurlRequestSnippet extends TemplatedSnippet {
 
 	private void writeHeaders(HttpHeaders headers, PrintWriter writer) {
 		for (Entry<String, List<String>> entry : headers.entrySet()) {
-			for (String header : entry.getValue()) {
+			if (!HttpHeaders.CONTENT_LENGTH.equalsIgnoreCase(entry.getKey())) {
-				writer.print(String.format(" -H '%s: %s'", entry.getKey(), header));
+				for (String header : entry.getValue()) {
+					writer.print(String.format(" -H '%s: %s'", entry.getKey(), header));
+				}
 			}
 		}
 	}

spring-restdocs-core/src/main/java/org/springframework/restdocs/operation/AbstractOperationMessage.java

@@ -35,7 +35,18 @@ abstract class AbstractOperationMessage {
 
 	AbstractOperationMessage(byte[] content, HttpHeaders headers) {
 		this.content = content == null ? new byte[0] : content;
-		this.headers = headers;
+		this.headers = createHeaders(content, headers);
+	}
+
+	private static HttpHeaders createHeaders(byte[] content, HttpHeaders input) {
+		HttpHeaders headers = new HttpHeaders();
+		if (input != null) {
+			headers.putAll(input);
+		}
+		if (content != null && content.length > 0 && headers.getContentLength() == -1) {
+			headers.setContentLength(content.length);
+		}
+		return headers;
 	}
 
 	public byte[] getContent() {

spring-restdocs-core/src/main/java/org/springframework/restdocs/operation/preprocess/ContentModifyingOperationPreprocessor.java

@@ -63,9 +63,12 @@ public class ContentModifyingOperationPreprocessor implements OperationPreproces
 	private HttpHeaders getUpdatedHeaders(HttpHeaders headers, byte[] updatedContent) {
 		HttpHeaders updatedHeaders = new HttpHeaders();
 		updatedHeaders.putAll(headers);
-		if (updatedHeaders.getContentLength() > -1) {
+		if (updatedContent.length > 0) {
 			updatedHeaders.setContentLength(updatedContent.length);
 		}
+		else {
+			updatedHeaders.remove(HttpHeaders.CONTENT_LENGTH);
+		}
 		return updatedHeaders;
 	}
 

spring-restdocs-core/src/test/java/org/springframework/restdocs/http/HttpRequestSnippetTests.java

@@ -75,30 +75,33 @@ public class HttpRequestSnippetTests {
 
 	@Test
 	public void postRequestWithContent() throws IOException {
+		String content = "Hello, world";
 		this.snippet.expectHttpRequest("post-request-with-content").withContents(
-				httpRequest(RequestMethod.POST, "/foo").header(HttpHeaders.HOST,
+				httpRequest(RequestMethod.POST, "/foo")
-						"localhost").content("Hello, world"));
+						.header(HttpHeaders.HOST, "localhost").content(content)
+						.header(HttpHeaders.CONTENT_LENGTH, content.getBytes().length));
 
 		new HttpRequestSnippet().document(new OperationBuilder(
 				"post-request-with-content", this.snippet.getOutputDirectory())
-				.request("http://localhost/foo").method("POST").content("Hello, world")
+				.request("http://localhost/foo").method("POST").content(content).build());
-				.build());
 	}
 
 	@Test
 	public void postRequestWithCharset() throws IOException {
 		String japaneseContent = "\u30b3\u30f3\u30c6\u30f3\u30c4";
+		byte[] contentBytes = japaneseContent.getBytes("UTF-8");
 		this.snippet.expectHttpRequest("post-request-with-charset").withContents(
 				httpRequest(RequestMethod.POST, "/foo")
 						.header(HttpHeaders.HOST, "localhost")
 						.header("Content-Type", "text/plain;charset=UTF-8")
+						.header(HttpHeaders.CONTENT_LENGTH, contentBytes.length)
 						.content(japaneseContent));
 
 		new HttpRequestSnippet().document(new OperationBuilder(
 				"post-request-with-charset", this.snippet.getOutputDirectory())
 				.request("http://localhost/foo").method("POST")
-				.header("Content-Type", "text/plain;charset=UTF-8")
+				.header("Content-Type", "text/plain;charset=UTF-8").content(contentBytes)
-				.content(japaneseContent.getBytes("UTF-8")).build());
+				.build());
 	}
 
 	@Test
@@ -117,14 +120,15 @@ public class HttpRequestSnippetTests {
 
 	@Test
 	public void putRequestWithContent() throws IOException {
+		String content = "Hello, world";
 		this.snippet.expectHttpRequest("put-request-with-content").withContents(
-				httpRequest(RequestMethod.PUT, "/foo").header(HttpHeaders.HOST,
+				httpRequest(RequestMethod.PUT, "/foo")
-						"localhost").content("Hello, world"));
+						.header(HttpHeaders.HOST, "localhost").content(content)
+						.header(HttpHeaders.CONTENT_LENGTH, content.getBytes().length));
 
 		new HttpRequestSnippet().document(new OperationBuilder(
 				"put-request-with-content", this.snippet.getOutputDirectory())
-				.request("http://localhost/foo").method("PUT").content("Hello, world")
+				.request("http://localhost/foo").method("PUT").content(content).build());
-				.build());
 	}
 
 	@Test

spring-restdocs-core/src/test/java/org/springframework/restdocs/http/HttpResponseSnippetTests.java

@@ -78,22 +78,27 @@ public class HttpResponseSnippetTests {
 
 	@Test
 	public void responseWithContent() throws IOException {
+		String content = "content";
 		this.snippet.expectHttpResponse("response-with-content").withContents(
-				httpResponse(HttpStatus.OK).content("content"));
+				httpResponse(HttpStatus.OK).content(content).header(
+						HttpHeaders.CONTENT_LENGTH, content.getBytes().length));
 		new HttpResponseSnippet().document(new OperationBuilder("response-with-content",
-				this.snippet.getOutputDirectory()).response().content("content").build());
+				this.snippet.getOutputDirectory()).response().content(content).build());
 	}
 
 	@Test
 	public void responseWithCharset() throws IOException {
 		String japaneseContent = "\u30b3\u30f3\u30c6\u30f3\u30c4";
+		byte[] contentBytes = japaneseContent.getBytes("UTF-8");
 		this.snippet.expectHttpResponse("response-with-charset").withContents(
-				httpResponse(HttpStatus.OK).header("Content-Type",
+				httpResponse(HttpStatus.OK)
-						"text/plain;charset=UTF-8").content(japaneseContent));
+						.header("Content-Type", "text/plain;charset=UTF-8")
+						.content(japaneseContent)
+						.header(HttpHeaders.CONTENT_LENGTH, contentBytes.length));
 		new HttpResponseSnippet().document(new OperationBuilder("response-with-charset",
 				this.snippet.getOutputDirectory()).response()
-				.header("Content-Type", "text/plain;charset=UTF-8")
+				.header("Content-Type", "text/plain;charset=UTF-8").content(contentBytes)
-				.content(japaneseContent.getBytes("UTF-8")).build());
+				.build());
 	}
 
 	@Test

spring-restdocs-core/src/test/java/org/springframework/restdocs/operation/preprocess/ContentModifyingOperationPreprocessorTests.java

@@ -71,16 +71,6 @@ public class ContentModifyingOperationPreprocessorTests {
 		assertThat(preprocessed.getContent(), is(equalTo("modified".getBytes())));
 	}
 
-	@Test
-	public void unknownContentLengthIsUnchanged() {
-		StandardOperationRequest request = new StandardOperationRequest(
-				URI.create("http://localhost"), HttpMethod.GET, "content".getBytes(),
-				new HttpHeaders(), new Parameters(),
-				Collections.<OperationRequestPart>emptyList());
-		OperationRequest preprocessed = this.preprocessor.preprocess(request);
-		assertThat(preprocessed.getHeaders().getContentLength(), is(equalTo(-1L)));
-	}
-
 	@Test
 	public void contentLengthIsUpdated() {
 		HttpHeaders httpHeaders = new HttpHeaders();

spring-restdocs-core/src/test/java/org/springframework/restdocs/test/SnippetMatchers.java

@@ -164,6 +164,12 @@ public final class SnippetMatchers {
 			return (T) this;
 		}
 
+		@SuppressWarnings("unchecked")
+		public T header(String name, long value) {
+			this.addLine(this.headerOffset++, name + ": " + value);
+			return (T) this;
+		}
+
 	}
 
 	/**

spring-restdocs-mockmvc/src/main/java/org/springframework/restdocs/mockmvc/RestDocumentationMockMvcConfigurer.java

@@ -29,7 +29,6 @@ import org.springframework.test.web.servlet.request.RequestPostProcessor;
 import org.springframework.test.web.servlet.setup.ConfigurableMockMvcBuilder;
 import org.springframework.test.web.servlet.setup.MockMvcConfigurer;
 import org.springframework.test.web.servlet.setup.MockMvcConfigurerAdapter;
-import org.springframework.util.StringUtils;
 import org.springframework.web.context.WebApplicationContext;
 
 /**
@@ -62,8 +61,7 @@ public class RestDocumentationMockMvcConfigurer extends MockMvcConfigurerAdapter
 	RestDocumentationMockMvcConfigurer(RestDocumentation restDocumentation) {
 		this.requestPostProcessor = new ConfigurerApplyingRequestPostProcessor(
 				restDocumentation, this.uriConfigurer, this.writerResolverConfigurer,
-				this.snippetConfigurer, new ContentLengthHeaderConfigurer(),
+				this.snippetConfigurer, this.templateEngineConfigurer);
-				this.templateEngineConfigurer);
 	}
 
 	/**
@@ -115,19 +113,6 @@ public class RestDocumentationMockMvcConfigurer extends MockMvcConfigurerAdapter
 		return this.requestPostProcessor;
 	}
 
-	private static final class ContentLengthHeaderConfigurer extends AbstractConfigurer {
-
-		@Override
-		void apply(MockHttpServletRequest request) {
-			long contentLength = request.getContentLengthLong();
-			if (contentLength > 0
-					&& !StringUtils.hasText(request.getHeader("Content-Length"))) {
-				request.addHeader("Content-Length", request.getContentLengthLong());
-			}
-		}
-
-	}
-
 	private static final class TemplateEngineConfigurer extends AbstractConfigurer {
 
 		private TemplateEngine templateEngine = new MustacheTemplateEngine(

spring-restdocs-mockmvc/src/test/java/org/springframework/restdocs/mockmvc/MockMvcOperationRequestFactoryTests.java

@@ -157,7 +157,8 @@ public class MockMvcOperationRequestFactoryTests {
 		OperationRequestPart part = request.getParts().iterator().next();
 		assertThat(part.getName(), is(equalTo("file")));
 		assertThat(part.getSubmittedFileName(), is(nullValue()));
-		assertThat(part.getHeaders().isEmpty(), is(true));
+		assertThat(part.getHeaders().size(), is(1));
+		assertThat(part.getHeaders().getContentLength(), is(4L));
 		assertThat(part.getContent(), is(equalTo(new byte[] { 1, 2, 3, 4 })));
 	}
 

spring-restdocs-mockmvc/src/test/java/org/springframework/restdocs/mockmvc/MockMvcRestDocumentationIntegrationTests.java

@@ -79,6 +79,7 @@ import static org.springframework.restdocs.test.SnippetMatchers.codeBlock;
 import static org.springframework.restdocs.test.SnippetMatchers.httpRequest;
 import static org.springframework.restdocs.test.SnippetMatchers.httpResponse;
 import static org.springframework.restdocs.test.SnippetMatchers.snippet;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
 
 /**
@@ -120,6 +121,21 @@ public class MockMvcRestDocumentationIntegrationTests {
 				"http-request.adoc", "http-response.adoc", "curl-request.adoc");
 	}
 
+	@Test
+	public void curlSnippetWithContent() throws Exception {
+		MockMvc mockMvc = MockMvcBuilders.webAppContextSetup(this.context)
+				.apply(documentationConfiguration(this.restDocumentation)).build();
+
+		mockMvc.perform(post("/").accept(MediaType.APPLICATION_JSON).content("content"))
+				.andExpect(status().isOk()).andDo(document("curl-snippet-with-content"));
+		assertThat(new File(
+				"build/generated-snippets/curl-snippet-with-content/curl-request.adoc"),
+				is(snippet().withContents(
+						codeBlock("bash").content(
+								"$ curl " + "'http://localhost:8080/' -i -X POST "
+										+ "-H 'Accept: application/json' -d 'content'"))));
+	}
+
 	@Test
 	public void linksSnippet() throws Exception {
 		MockMvc mockMvc = MockMvcBuilders.webAppContextSetup(this.context)
@@ -298,24 +314,27 @@ public class MockMvcRestDocumentationIntegrationTests {
 								removeHeaders("a"),
 								replacePattern(pattern, "\"<<beta>>\""))));
 
+		String original = "{\"a\":\"alpha\",\"links\":[{\"rel\":\"rel\","
+				+ "\"href\":\"href\"}]}";
 		assertThat(
 				new File("build/generated-snippets/original-response/http-response.adoc"),
 				is(snippet().withContents(
 						httpResponse(HttpStatus.OK)
 								.header("a", "alpha")
 								.header("Content-Type", "application/json")
-								.content(
+								.header(HttpHeaders.CONTENT_LENGTH,
-										"{\"a\":\"alpha\",\"links\":[{\"rel\":\"rel\","
+										original.getBytes().length).content(original))));
-												+ "\"href\":\"href\"}]}"))));
+		String prettyPrinted = String.format("{%n  \"a\" : \"<<beta>>\",%n  \"links\" : "
+				+ "[ {%n    \"rel\" : \"rel\",%n    \"href\" : \"...\"%n  } ]%n}");
 		assertThat(
 				new File(
 						"build/generated-snippets/preprocessed-response/http-response.adoc"),
 				is(snippet().withContents(
-						httpResponse(HttpStatus.OK).header("Content-Type",
+						httpResponse(HttpStatus.OK)
-								"application/json").content(
+								.header("Content-Type", "application/json")
-								String.format("{%n  \"a\" : \"<<beta>>\",%n  \"links\" :"
+								.header(HttpHeaders.CONTENT_LENGTH,
-										+ " [ {%n    \"rel\" : \"rel\",%n    \"href\" :"
+										prettyPrinted.getBytes().length)
-										+ " \"...\"%n  } ]%n}")))));
+								.content(prettyPrinted))));
 	}
 
 	@Test

spring-restdocs-mockmvc/src/test/java/org/springframework/restdocs/mockmvc/RestDocumentationConfigurerTests.java

@@ -27,7 +27,6 @@ import org.springframework.test.web.servlet.request.RequestPostProcessor;
 import org.springframework.web.context.request.RequestContextHolder;
 import org.springframework.web.context.request.ServletRequestAttributes;
 
-import static org.hamcrest.CoreMatchers.equalTo;
 import static org.hamcrest.CoreMatchers.is;
 import static org.hamcrest.CoreMatchers.nullValue;
 import static org.junit.Assert.assertEquals;
@@ -94,17 +93,6 @@ public class RestDocumentationConfigurerTests {
 		assertThat(this.request.getHeader("Content-Length"), is(nullValue()));
 	}
 
-	@Test
-	public void contentLengthHeaderIsSetWhenRequestHasContent() {
-		RequestPostProcessor postProcessor = new RestDocumentationMockMvcConfigurer(
-				this.restDocumentation).beforeMockMvcCreated(null, null);
-		byte[] content = "Hello, world".getBytes();
-		this.request.setContent(content);
-		postProcessor.postProcessRequest(this.request);
-		assertThat(this.request.getHeader("Content-Length"),
-				is(equalTo(Integer.toString(content.length))));
-	}
-
 	private void assertUriConfiguration(String scheme, String host, int port) {
 		assertEquals(scheme, this.request.getScheme());
 		assertEquals(host, this.request.getServerName());