NEW: Add status code comment to testsession/start output.

testsession/start now includes a comment of the form <!-- SUCCESS: DBNAME=DatabaseName -->,
which can be used by behat and other consumers to validate that the tesession was actually
started.

It's included the database name in its output, which is a small piece of information
disclosure, but not a big deal compared to the generally dev-only nature of this module.

It requires a fix to Cookie::set(), to ensure that set cookies also apperar immediately
in $_COOKIE.  Otherwise the call to DB::get_alternative_database_name() after it is set
won't return a value.

code/TestSessionController.php

@@ -44,6 +44,15 @@ class TestSessionController extends Controller {
 		return $this->renderWith('TestSession_start');
 	}
 
+	public function DatabaseName() {
+		if($dbname = DB::get_alternative_database_name()) {
+			return $dbname;
+		} else {
+			$db = DB::getConn();
+			if(method_exists($db, 'currentDatabase')) return $db->currentDatabase();
+		}
+	}
+
 	public function set($request) {
 		if(!SapphireTest::using_temp_db()) {
 			throw new LogicException(

templates/TestSession_start.ss

@@ -1,3 +1,4 @@
+<!-- SUCCESS: DBNAME=$DatabaseName -->
 <p>
 	Started testing session. 
 	<% if Fixture %>Loaded fixture "$Fixture" into database.<% end_if %>