function testBuilder()
{
$str = new StringBuilder();
$str->write('Hello World');
$this->assertEquals('e', $str[1]);
$this->assertCount(strlen('Hello World'), $str);
$this->assertFalse(isset($str[11]));
$this->assertTrue(isset($str[10]));
$str[5] = '_';
$this->assertEquals('Hello_World', (string) $str);
$this->assertEquals(11, $str->getLength());
$this->assertEquals(5, $str->indexOf('_'));
$this->assertEmpty((string) $str->clean());
$this->assertEquals('Hello Masoud', (new StringBuilder('Hello %s'))->inject('Masoud'));
$this->assertEquals('Hel_lo', (new StringBuilder('Hello'))->insert(3, '_'));
$this->assertEquals('Dear, Masoud', (new StringBuilder())->write('Dear, %s', 'Masoud')->toString());
}