tweak tests and add some commenting

jetty-rewrite/src/main/java/org/eclipse/jetty/rewrite/handler/ValidUrlRule.java

@@ -25,6 +25,15 @@ import javax.servlet.http.HttpServletResponse;
 
 import org.eclipse.jetty.util.URIUtil;
 
+/**
+ * This rule can be used to protect against invalid unicode characters in a url making it into applications.
+ *
+ * The logic is as follows.
+ * 
+ * - if decoded uri character is an iso control character return code/reason
+ * - if no UnicodeBlock is found for character return code/reason
+ * - if character is in UnicodeBlock.SPECIALS return code/reason
+ */
 public class ValidUrlRule extends Rule
 {
     String _code = "400";
@@ -81,10 +90,12 @@ public class ValidUrlRule extends Rule
                     response.setStatus(code);
                 }
 
+                // we have matched, return target and consider it is handled
                 return target;
             }
         }
 
+        // we have not matched so return null
         return null;
     }
 

jetty-rewrite/src/test/java/org/eclipse/jetty/rewrite/handler/ValidUrlRuleTest.java

@@ -58,14 +58,16 @@ public class ValidUrlRuleTest extends AbstractRuleTestCase
     }
 
     @Test
-    public void testInvalidUrl2() throws Exception
+    public void testInvalidUrlWithReason() throws Exception
     {
-        _rule.setCode("404");
+        _rule.setCode("405");
+        _rule.setReason("foo");
         _request.setRequestURI("/%00/");
         
         String result = _rule.matchAndApply(_request.getRequestURI(), _request, _response);
 
-        assertEquals(404,_response.getStatus());
+        assertEquals(405,_response.getStatus());
+        assertEquals("foo",_response.getReason());
     }
     
     @Test