Iterable return types should return empty array by default

src/Framework/MockObject/Invocation.php

@@ -152,7 +152,7 @@ public function generateReturnValue()
             case 'generator':
             case 'iterable':
                 $generator = static function () {
-                    yield;
+                    yield from [];
                 };
 
                 return $generator();

tests/end-to-end/mock-objects/generator/return_type_declarations_generator_empty_by_default.phpt

@@ -0,0 +1,27 @@
+--TEST--
+Iterable return types should return empty array by default
+--FILE--
+<?php declare(strict_types=1);
+interface Foo
+{
+    public function forTraversable(): traversable;
+    public function forGenerator(): Generator;
+    public function forIterable(): iterable;
+}
+
+require __DIR__ . '/../../../../vendor/autoload.php';
+
+$generator = new \PHPUnit\Framework\MockObject\Generator;
+
+$mock = $generator->getMock('Foo');
+
+var_dump(iterator_to_array($mock->forTraversable()));
+var_dump(iterator_to_array($mock->forGenerator()));
+var_dump(iterator_to_array($mock->forIterable()));
+--EXPECTF--
+array(0) {
+}
+array(0) {
+}
+array(0) {
+}