✅ Add tests for VisitorMany and VisitorBase

tests/Query/TraverserTest.php

@@ -133,7 +133,20 @@ public function test_it_traverses_a_query_document()
                 array($this->equalTo($document))
             );
 
-        $traverser = new Traverser($visitor);
+        $countingVisitor = new VisitorCounting;
+        $visitors = new VisitorMany(
+            array(
+                $countingVisitor,
+                $visitor,
+            )
+        );
+
+        $traverser = new Traverser($visitors);
         $traverser->traverse($document);
+
+        $this->assertEquals(
+            21,
+            $countingVisitor->getCount()
+        );
     }
 }

tests/Query/VisitorCounting.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace HansOtt\GraphQL\Query;
+
+final class VisitorCounting extends VisitorBase
+{
+    private $count = 0;
+
+    public function getCount()
+    {
+        return $this->count;
+    }
+
+    public function enterNode(Node $node)
+    {
+        $this->count++;
+    }
+}