PHP Unit testing and mocking a file system scandir()

Question

I have a method in a class that scans a directory and creates an array of all the subdirectories. It's pretty simple and works great. However, I would like to add a unit test for this method and I am having a hard time figuring out how.

Here's my problem: I can create a virtual file system using vfsstream and it works fine. However, I can't pass that to my class to create an array from. It needs a real directory to scan. I want to test against a controlled directory (obviously so I know exactly what will the be result of every scan so I can test it). The scanned directory in production may change frequently.

So, my only solution is to create a test-specific fake directory in my test folders, pass that path to my scanner, and then check it against what I know to be in that fake directory. Is this best practice or am I missing something?

Thank you!

Here is some code: The Test

function testPopulateAuto() 
{ 
    $c = new \Director\Core\Components\Components; 

    // The structure of the file system I am checking against. This is what I want to generate. 
    $check = array( 
        'TestFolder1', 
        'TestFolder2', 
    );     

    $path = dirname( __FILE__ ) . "/test-file-system/"; // Contains TestFolder1 and TestFolder1 
    $list = $c->generateList( $path ); // Scans the path and returns an array that should be identical to $check 

    $this->assertEquals($check, $list); 
}  

Answer 1

Sorry if I misunderstood your question, but scandir should work with custom stream. Example:

$structure = array(
        'tmp' => array(
                'music' => array(
                        'wawfiles' => array(
                                'mp3'                      => array(),
                                'hello world.waw'          => 'nice song',
                                'abc.waw'                  => 'bad song',
                                'put that cookie down.waw' => 'best song ever',
                                "zed's dead baby.waw"      => 'another cool song'
                        )
                )
        )
);
$vfs = vfsStream::setup('root');
vfsStream::create($structure, $vfs);

$music = vfsStream::url('root/tmp/music/wawfiles');

var_dump(scandir($music));

Output:

array(5) {
  [0]=>
  string(7) "abc.waw"
  [1]=>
  string(15) "hello world.waw"
  [2]=>
  string(3) "mp3"
  [3]=>
  string(24) "put that cookie down.waw"
  [4]=>
  string(19) "zed's dead baby.waw"
}