Return null instead of empty cookies array in Spring MVC Test

Prior to this commit, MockHttpServletRequestBuilder always supplied an
array of cookies to the MockHttpServletRequest that it built, even if
the array was empty.

However, this violates the contract of HttpServletRequest. According to
the Servlet API, the getCookies() method "returns null if no cookies
were sent."

This commit ensures that MockHttpServletRequestBuilder no longer
configures an empty array of cookies in the mock request that it builds.

Issue: SPR-13314

spring-test/src/main/java/org/springframework/test/web/servlet/request/MockHttpServletRequestBuilder.java

@@ -574,6 +574,7 @@ public class MockHttpServletRequestBuilder
 		}
 
 		request.setMethod(this.method.name());
+
 		for (String name : this.headers.keySet()) {
 			for (Object value : this.headers.get(name)) {
 				request.addHeader(name, value);
@@ -604,16 +605,20 @@ public class MockHttpServletRequestBuilder
 
 		request.setContentType(this.contentType);
 		request.setContent(this.content);
-		request.setCookies(this.cookies.toArray(new Cookie[this.cookies.size()]));
+		request.setCharacterEncoding(this.characterEncoding);
+
+		if (!ObjectUtils.isEmpty(this.cookies)) {
+			request.setCookies(this.cookies.toArray(new Cookie[this.cookies.size()]));
+		}
 
 		if (this.locale != null) {
 			request.addPreferredLocale(this.locale);
 		}
-		request.setCharacterEncoding(this.characterEncoding);
 
 		if (this.secure != null) {
 			request.setSecure(this.secure);
 		}
+
 		request.setUserPrincipal(this.principal);
 
 		for (String name : this.attributes.keySet()) {

spring-test/src/test/java/org/springframework/mock/web/MockHttpServletRequestTests.java

@@ -28,6 +28,8 @@ import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 
+import javax.servlet.http.Cookie;
+
 import org.junit.Test;
 
 import org.springframework.util.StreamUtils;
@@ -200,6 +202,26 @@ public class MockHttpServletRequestTests {
 		assertEquals(0, request.getParameterMap().size());
 	}
 
+	@Test
+	public void cookies() {
+		Cookie cookie1 = new Cookie("foo", "bar");
+		Cookie cookie2 = new Cookie("baz", "qux");
+		request.setCookies(cookie1, cookie2);
+
+		Cookie[] cookies = request.getCookies();
+
+		assertEquals(2, cookies.length);
+		assertEquals("foo", cookies[0].getName());
+		assertEquals("bar", cookies[0].getValue());
+		assertEquals("baz", cookies[1].getName());
+		assertEquals("qux", cookies[1].getValue());
+	}
+
+	@Test
+	public void noCookies() {
+		assertNull(request.getCookies());
+	}
+
 	@Test
 	public void defaultLocale() {
 		Locale originalDefaultLocale = Locale.getDefault();

spring-test/src/test/java/org/springframework/test/web/servlet/request/MockHttpServletRequestBuilderTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2015 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.
@@ -29,6 +29,7 @@ import javax.servlet.http.Cookie;
 
 import org.junit.Before;
 import org.junit.Test;
+
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.MediaType;
@@ -42,21 +43,22 @@ import org.springframework.web.servlet.support.SessionFlashMapManager;
 import static org.junit.Assert.*;
 
 /**
- * Tests building a MockHttpServletRequest with {@link MockHttpServletRequestBuilder}.
+ * Unit tests for building a {@link MockHttpServletRequest} with
+ * {@link MockHttpServletRequestBuilder}.
  *
  * @author Rossen Stoyanchev
+ * @author Sam Brannen
  */
 public class MockHttpServletRequestBuilderTests {
 
-	private MockHttpServletRequestBuilder builder;
+	private final ServletContext servletContext = new MockServletContext();
 
-	private ServletContext servletContext;
+	private MockHttpServletRequestBuilder builder;
 
 
 	@Before
 	public void setUp() {
 		this.builder = new MockHttpServletRequestBuilder(HttpMethod.GET, "/foo/bar");
-		servletContext = new MockServletContext();
 	}
 
 	@Test
@@ -354,6 +356,12 @@ public class MockHttpServletRequestBuilderTests {
 		assertEquals("qux", cookies[1].getValue());
 	}
 
+	@Test
+	public void noCookies() {
+		MockHttpServletRequest request = this.builder.buildRequest(this.servletContext);
+		assertNull(request.getCookies());
+	}
+
 	@Test
 	public void locale() {
 		Locale locale = new Locale("nl", "nl");