public function test_to_json_include_root()
 {
     ActiveRecord\JsonSerializer::$include_root = true;
     $this->assert_not_null(json_decode(Book::find(1)->to_json())->book);
 }
 public function testToJsonIncludeRoot()
 {
     ActiveRecord\JsonSerializer::$includeRoot = true;
     $this->assertNotNull(json_decode(Book::find(1)->toJson())->book);
 }