Add MockHttpServletResponse.getDateHeader

This change adds a new `getDateHeader` method that converts date header
Strings to long values - making tests more readable.

This feature is also documented in the "what's new section" for 4.2.

spring-test/src/main/java/org/springframework/mock/web/MockHttpServletResponse.java

@@ -23,6 +23,7 @@ import java.io.OutputStreamWriter;
 import java.io.PrintWriter;
 import java.io.UnsupportedEncodingException;
 import java.io.Writer;
+import java.text.ParseException;
 import java.text.SimpleDateFormat;
 import java.util.ArrayList;
 import java.util.Collection;
@@ -493,6 +494,17 @@ public class MockHttpServletResponse implements HttpServletResponse {
 		setHeaderValue(name, formatDate(value));
 	}
 
+	public long getDateHeader(String name) {
+		SimpleDateFormat dateFormat = new SimpleDateFormat(DATE_FORMAT, Locale.US);
+		dateFormat.setTimeZone(GMT);
+		try {
+			return dateFormat.parse(getHeader(name)).getTime();
+		} catch (ParseException exception) {
+			throw new IllegalArgumentException(
+					"Value for header '" + name + "' is not a valid Date: " + getHeader(name));
+		}
+	}
+
 	@Override
 	public void addDateHeader(String name, long value) {
 		addHeaderValue(name, formatDate(value));

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

@@ -36,6 +36,7 @@ import static org.junit.Assert.*;
  * @author Rossen Stoyanchev
  * @author Rob Winch
  * @author Sam Brannen
+ * @author Brian Clozel
  * @since 19.02.2006
  */
 public class MockHttpServletResponseTests {
@@ -253,6 +254,21 @@ public class MockHttpServletResponseTests {
 		assertEquals("Tue, 21 Jul 2015 10:00:01 GMT", response.getHeaders("Last-Modified").get(1));
 	}
 
+	@Test
+	public void getDateHeader() {
+		long time = 1437472800000L;
+		response.setDateHeader("Last-Modified", time);
+		assertEquals("Tue, 21 Jul 2015 10:00:00 GMT", response.getHeader("Last-Modified"));
+		assertEquals(time, response.getDateHeader("Last-Modified"));
+	}
+
+	@Test(expected = IllegalArgumentException.class)
+	public void getInvalidDateHeader() {
+		response.setHeader("Last-Modified", "invalid");
+		assertEquals("invalid", response.getHeader("Last-Modified"));
+		response.getDateHeader("Last-Modified");
+	}
+
 	/**
 	 * SPR-10414
 	 */

src/asciidoc/whats-new.adoc

@@ -618,4 +618,6 @@ public @interface MyTestConfig {
   allowing common test database configuration to be reused in different
   ++ApplicationContext++s within a test suite.
 ** See <<jdbc-embedded-database-unique-names>> for details.
+* `MockHttpServletRequest` and `MockHttpServletResponse` now better supports
+  date header formatting `getDateHeader` and `setDateHeader` methods.