fix when search service not exists

throw an error when the search service name does not exists.
+ test

Search/SearchProvider.php

@@ -63,7 +63,7 @@ class SearchProvider
             throw new ParsingException('You should not have more than one domain');
         }
         
-        return isset($terms[1][0]) ? $terms[1][0] : '';
+        return isset($terms[1][0]) ? $terms[1][0] : NULL;
     }
     
     /**
@@ -89,15 +89,20 @@ class SearchProvider
         return $results;
     }
 
-    /*
+    /**
      * return search services with a specific name, defined in service
      * definition.
      *
      * @return SearchInterface
+     * @throws UnknowSearchNameException if not exists
      */
     public function getByName($name)
     {
-        return $this->searchServices[$name];
+        if (isset($this->searchServices[$name])) {
+            return $this->searchServices; 
+        } else {
+          throw new UnknowSearchNameException($name);
+        }
     }
 
     public function addSearchService(SearchInterface $service, $name)

Search/UnknowSearchNameException.php

@@ -0,0 +1,35 @@
+<?php
+
+/*
+ * Chill is a software for social workers
+ * Copyright (C) 2014 Julien Fastré <julien.fastre@champs-libres.coop>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+namespace Chill\MainBundle\Search;
+
+/**
+ * Throw by search provider when the search name is not found
+ *
+ * @author Julien Fastré <julien.fastre@champs-libres.coop>
+ */
+class UnknowSearchNameException extends \Exception
+{
+    public function __construct($name)
+    {
+        parent::__construct( "The module search with name $name "
+              . "is not found");
+    }
+}

Tests/Search/SearchProviderTest.php

@@ -29,6 +29,14 @@ class SearchProviderTest extends \PHPUnit_Framework_TestCase
         $this->search = new SearchProvider();
     }
     
+    /**
+     * @expectedException \Chill\MainBundle\Search\UnknowSearchNameException
+     */
+    public function testInvalidSearchName()
+    {
+        $this->search->getByName("invalid name");
+    }
+    
     public function testDomain()
     {
         $term = $this->p("@person is not my name");