core/tests/WritePermissionsTest.php

<?php

class WritePermissionsTest extends TestCase
{
    public function testStorageDir()
    {
        $this->writeToDir(storage_path('test.txt'));
    }

    public function testLogsDir()
    {
        $this->writeToDir(storage_path('logs/test.txt'));
    }

    public function testFrameworkDir()
    {
        $this->writeToDir(storage_path('framework/test.txt'));
    }

    public function testBootstrapCacheDir()
    {
        $this->writeToDir(storage_path('../bootstrap/cache/test.txt'));
    }

    public function testUploadDir()
    {
        $this->writeToDir(config('app.upload_path').'/test.txt');
    }

    /**
     * Create and delete some file
     *
     * @param $path
     */
    protected function writeToDir($file)
    {
        $content = uniqid();
        $bytesWritten = file_put_contents($file, $content);

        // test writing
        $this->assertNotFalse($bytesWritten);

        // test deleting
        $deleted = @unlink($file);
        $this->assertTrue($deleted);
    }
}