php - How to mock readonly directory using PHPUnit and VFSstream -

i have simple open (file) method should throw exception if fails open or create file in given path:

const err_msg_open_file = 'failed open or create file @ %s';  public function open($filepath) {     ini_set('auto_detect_line_endings', true);      if (false !== ($this->handler = @fopen($filepath, 'c+'))) {         return true;     } else {         throw new \exception(             sprintf(self::err_msg_open_file, $filepath)         );     } } 

there unit-test around using phpunit , vfsstream:

$structure = [         'sample.csv' => file_get_contents(__dir__ . '/../samplefiles/small.csv')     ];  $this->root = vfsstream::setup('exampledir', null, $structure);  $existingfilepath = vfsstream::url('exampledir') . directory_separator . 'sample.csv';  $this->file = new file(); $this->file->open($existingfilepath); 

the above setup creates virtual directory structor containing mock file (read/cloned existing csv file) , satisfy open method's requirement open file. , if pass different path (none existing file) created in same virtual structor.

now in order cover exception want add ready-only directory existing structor, lets folder belong user , don't have write permission on it, when try open non existing file in folder, attempt creating 1 should fail , open method should throw exception.

the problem is,.... don't know how :d

any advice, hint , guidance appreciated :)

you point mock directory's url incorrect path.

$existingfilepath = vfsstream::url('badexampledir') . directory_separator . 'incorrect.csv'; 

considering badexampledir never been setup method fail create file in it.