Test for lazy interface initialization + minor related tweak

Author: vladar

src/Type/Definition/InterfaceType.php

@@ -60,10 +60,10 @@ public static function addImplementationToInterfaces(ObjectType $impl)
      */
     public static function loadImplementationToInterfaces()
     {
-        foreach (self::$_lazyLoadImplementations as $i => &$lazyLoadImplementation) {
-            call_user_func($lazyLoadImplementation);
-            unset(self::$_lazyLoadImplementations[$i]);
+        foreach (self::$_lazyLoadImplementations as $lazyLoadImplementation) {
+            $lazyLoadImplementation();
         }
+        self::$_lazyLoadImplementations = [];
     }
 
     /**

tests/Type/DefinitionTest.php

@@ -232,22 +232,24 @@ public function testIncludesInterfaceSubtypesInTheTypeMap()
     public function testIncludesInterfacesThunkSubtypesInTheTypeMap()
     {
         // includes interfaces' thunk subtypes in the type map
-        $someInterface = new InterfaceType([
-            'name' => 'SomeInterface',
-            'fields' => [
-                'f' => ['type' => Type::int()]
-            ]
-        ]);
+        $someInterface = null;
 
         $someSubtype = new ObjectType([
             'name' => 'SomeSubtype',
             'fields' => [
                 'f' => ['type' => Type::int()]
             ],
-            'interfaces' => function() use ($someInterface) { return [$someInterface]; },
+            'interfaces' => function() use (&$someInterface) { return [$someInterface]; },
             'isTypeOf' => function() {return true;}
         ]);
 
+        $someInterface = new InterfaceType([
+            'name' => 'SomeInterface',
+            'fields' => [
+                'f' => ['type' => Type::int()]
+            ]
+        ]);
+
         $schema = new Schema(new ObjectType([
             'name' => 'Query',
             'fields' => [