Valitron\Validator::withData PHP Method

    public function withData($data, $fields = array())
    {
        $clone = clone $this;
        $clone->reset();
        $clone->_fields = !empty($fields) ? array_intersect_key($data, array_flip($fields)) : $data;
        return $clone;
    }

 public function testWithData()
 {
     $v = new Validator(array());
     $v->rule('required', 'name');
     //validation failed, so must have errors
     $this->assertFalse($v->validate());
     $this->assertNotEmpty($v->errors());
     //create copy with different data
     $v2 = $v->withData(array('name' => 'Chester Tester'));
     $this->assertTrue($v2->validate());
     $this->assertEmpty($v2->errors());
 }