public function testThatSelectDoesNotMaintainReferences(\Pinq\ITraversable $traversable) { $data = $this->makeRefs(range('Z', 'A')); $traversable->append($data)->select(function &(&$i) { return $i; })->iterate(function (&$i) { $i .= $i; }); $this->assertSame(range('Z', 'A'), $data); }