#342 - Polishing.

Extracted exception message into a constant. Added author where necessary and extended copyright headers. Fixed import order. Moved unit test into ControllerLinkBuilderUnitTest. Tweaked it to use JUnit rule.

Original pull request: #344.

src/main/java/org/springframework/hateoas/mvc/ControllerLinkBuilder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2014 the original author or authors.
+ * Copyright 2012-2015 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.
@@ -17,10 +17,11 @@ package org.springframework.hateoas.mvc;
 
 import static org.springframework.util.StringUtils.*;
 
-import javax.servlet.http.HttpServletRequest;
 import java.lang.reflect.Method;
 import java.net.URI;
 
+import javax.servlet.http.HttpServletRequest;
+
 import org.springframework.hateoas.Link;
 import org.springframework.hateoas.core.AnnotationMappingDiscoverer;
 import org.springframework.hateoas.core.DummyInvocationUtils;
@@ -41,9 +42,11 @@ import org.springframework.web.util.UriTemplate;
  * 
  * @author Oliver Gierke
  * @author Kamill Sokol
+ * @author Greg Turnquist
  */
 public class ControllerLinkBuilder extends LinkBuilderSupport<ControllerLinkBuilder> {
 
+	private static final String REQUEST_ATTRIBUTES_MISSING = "Could not find current request via RequestContextHolder. Is this being called from a Spring MVC handler?";
 	private static final MappingDiscoverer DISCOVERER = new AnnotationMappingDiscoverer(RequestMapping.class);
 	private static final ControllerLinkBuilderFactory FACTORY = new ControllerLinkBuilderFactory();
 
@@ -236,7 +239,7 @@ public class ControllerLinkBuilder extends LinkBuilderSupport<ControllerLinkBuil
 	private static HttpServletRequest getCurrentRequest() {
 
 		RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
-		Assert.state(requestAttributes != null, "Could not find current request via RequestContextHolder. Is this being called from a Spring MVC handler?");
+		Assert.state(requestAttributes != null, REQUEST_ATTRIBUTES_MISSING);
 		Assert.isInstanceOf(ServletRequestAttributes.class, requestAttributes);
 		HttpServletRequest servletRequest = ((ServletRequestAttributes) requestAttributes).getRequest();
 		Assert.state(servletRequest != null, "Could not find current HttpServletRequest");

src/test/java/org/springframework/hateoas/mvc/ControllerLinkBuilderUnitTest.java

@@ -15,8 +15,8 @@
  */
 package org.springframework.hateoas.mvc;
 
+import static org.hamcrest.MatcherAssert.*;
 import static org.hamcrest.Matchers.*;
-import static org.junit.Assert.*;
 import static org.springframework.hateoas.mvc.ControllerLinkBuilder.*;
 
 import java.lang.reflect.Method;
@@ -24,7 +24,9 @@ import java.util.Arrays;
 import java.util.List;
 
 import org.hamcrest.Matchers;
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 import org.mockito.Mockito;
 import org.springframework.hateoas.Identifiable;
 import org.springframework.hateoas.Link;
@@ -35,6 +37,7 @@ import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.context.request.RequestContextHolder;
 import org.springframework.web.util.UriComponents;
 import org.springframework.web.util.UriComponentsBuilder;
 
@@ -45,9 +48,12 @@ import org.springframework.web.util.UriComponentsBuilder;
  * @author Dietrich Schulten
  * @author Kamill Sokol
  * @author Oemer Yildiz
+ * @author Greg Turnquist
  */
 public class ControllerLinkBuilderUnitTest extends TestUtils {
 
+	public @Rule ExpectedException exception = ExpectedException.none();
+
 	@Test
 	public void createsLinkToControllerRoot() {
 
@@ -435,6 +441,22 @@ public class ControllerLinkBuilderUnitTest extends TestUtils {
 		assertThat(link.getHref(), endsWith("/bar"));
 	}
 
+	/**
+	 * @see #342
+	 */
+	@Test
+	public void mentionsRequiredUsageWithinWebRequestInException() {
+
+		exception.expect(IllegalStateException.class);
+		exception.expectMessage("request");
+		exception.expectMessage("Spring MVC");
+
+		RequestContextHolder.setRequestAttributes(null);
+
+		linkTo(methodOn(ControllerLinkBuilderUnitTest.PersonsAddressesController.class, 15).getAddressesForCountry("DE"))
+				.withSelfRel();
+	}
+
 	private static UriComponents toComponents(Link link) {
 		return UriComponentsBuilder.fromUriString(link.getHref()).build();
 	}