Respect\Validation\Rules\Extension::validate PHP Method

    public function validate($input)
    {
        if ($input instanceof SplFileInfo) {
            return $input->getExtension() == $this->extension;
        }
        if (!is_string($input)) {
            return false;
        }
        return pathinfo($input, PATHINFO_EXTENSION) == $this->extension;
    }

 public function testShouldInvalidWhenNotStringNorSplFileInfo()
 {
     $nonFile = array(__FILE__);
     $rule = new Extension('php');
     $this->assertFalse($rule->validate($nonFile));
 }