问PHPUnit setUp方法

EN

use PHPUnit\Framework\TestCase;

class StringTest extends TestCase
{
    protected $stack = '';

    public function testModify()
    {
        $this->stack .= 'modify';
        $this->assertEquals('modify', $this->stack);
    }

    public function testEmpty()
    {
        $this->assertEquals('', $this->stack);
    }

}