FEATURE: Allow filter mode by not forcing a search term

Classes/Domain/Model/SearchRequest.php

@@ -66,7 +66,7 @@ class SearchRequest implements SearchRequestInterface
     /**
      * @param string $query
      */
-    public function __construct($query)
+    public function __construct($query = '')
     {
         $this->query = (string) $query;
     }

Classes/Domain/Search/QueryFactory.php

@@ -105,6 +105,10 @@ class QueryFactory
      */
     protected function addSearch(SearchRequestInterface $searchRequest, array &$query)
     {
+        if (trim($searchRequest->getSearchTerm()) === '') {
+            return;
+        }
+
         $query = ArrayUtility::setValueByPath(
             $query,
             'query.bool.must.0.match._all.query',

Tests/Unit/Domain/Search/QueryFactoryTest.php

@@ -324,4 +324,23 @@ class QueryFactoryTest extends AbstractUnitTestCase
             'Boosts were not added to query.'
         );
     }
+
+    /**
+     * @test
+     */
+    public function emptySearchStringWillNotAddSearchToQuery()
+    {
+        $searchRequest = new SearchRequest();
+
+        $this->configuration->expects($this->any())
+            ->method('get')
+            ->will($this->throwException(new InvalidArgumentException));
+
+        $query = $this->subject->create($searchRequest);
+        $this->assertInstanceOf(
+            stdClass,
+            $query->toArray()['query']['match_all'],
+            'Empty search request does not create expected query.'
+        );
+    }
 }