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); }