public function testFill()
{
$str = "S";
Arrays::fill($str, 1, 20, "");
$this->assertEquals(20, mb_strlen($str));
$this->assertEquals("S", $str[0]);
$this->assertEquals("", $str[19]);
$str = "S";
Arrays::fill($str, "");
$this->assertEquals(1, mb_strlen($str));
$this->assertEquals("", $str);
$array = [1, 2, 3];
Arrays::fill($array, null);
$this->assertEquals(3, count($array));
$this->assertEquals([null, null, null], $array);
}
