public function testAttributes()
 {
     $exception = new Exception('', $previous = new Exception());
     $attributes = ['index-01' => 'value-01', 'index-02' => 'value-02'];
     foreach ($attributes as $i => $v) {
         $this->assertFalse($exception->hasAttribute($i));
         $exception->setAttribute($i, $v);
         $this->assertSame($v, $exception->getAttribute($i));
         $this->assertTrue($exception->hasAttribute($i));
     }
 }