trait TestFileCreationTrait

trait TestFileCreationTrait {
    
    /**
     * Whether the files were copied to the test files directory.
     *
     * @var bool
     */
    protected $generatedTestFiles = FALSE;
    
    /**
     * Gets a list of files that can be used in tests.
     *
     * The first time this method is called, it will call
     * $this->generateFile() to generate binary and ASCII text files in the
     * public:// directory. It will also copy all files in
     * core/tests/fixtures/files to public://. These contain image, SQL, PHP,
     * JavaScript, and HTML files.
     *
     * All filenames are prefixed with their type and have appropriate extensions:
     * - text-*.txt
     * - binary-*.txt
     * - html-*.html and html-*.txt
     * - image-*.png, image-*.jpg, and image-*.gif
     * - javascript-*.txt and javascript-*.script
     * - php-*.txt and php-*.php
     * - sql-*.txt and sql-*.sql
     *
     * Any subsequent calls will not generate any new files, or copy the files
     * over again. However, if a test class adds a new file to public:// that
     * is prefixed with one of the above types, it will get returned as well, even
     * on subsequent calls.
     *
     * @param $type
     *   File type, possible values: 'binary', 'html', 'image', 'javascript',
     *   'php', 'sql', 'text'.
     * @param $size
     *   (optional) File size in bytes to match. Defaults to NULL, which will not
     *   filter the returned list by size.
     *
     * @return object[]
     *   List of files in public:// that match the filter(s). Each file is an
     *   object with 'uri', 'filename', and 'name' properties.
     */
    protected function getTestFiles($type, $size = NULL) {
        
        /** @var \Drupal\Core\File\FileSystemInterface $file_system */
        $file_system = \Drupal::service('file_system');
        if (empty($this->generatedTestFiles)) {
            // Generate binary test files.
            $lines = [
                64,
                1024,
            ];
            $count = 0;
            foreach ($lines as $line) {
                $this->generateFile('binary-' . $count++, 64, $line, 'binary');
            }
            // Generate ASCII text test files.
            $lines = [
                16,
                256,
                1024,
                2048,
                20480,
            ];
            $count = 0;
            foreach ($lines as $line) {
                $this->generateFile('text-' . $count++, 64, $line, 'text');
            }
            // Copy other test files from fixtures.
            $original = \Drupal::root() . '/core/tests/fixtures/files';
            $files = $file_system->scanDirectory($original, '/(html|image|javascript|php|sql)-.*/');
            foreach ($files as $file) {
                $file_system->copy($file->uri, PublicStream::basePath());
            }
            $this->generatedTestFiles = TRUE;
        }
        $files = [];
        // Make sure type is valid.
        if (in_array($type, [
            'binary',
            'html',
            'image',
            'javascript',
            'php',
            'sql',
            'text',
        ])) {
            $files = $file_system->scanDirectory('public://', '/' . $type . '\\-.*/');
            // If size is set then remove any files that are not of that size.
            if ($size !== NULL) {
                foreach ($files as $file) {
                    $stats = stat($file->uri);
                    if ($stats['size'] != $size) {
                        unset($files[$file->uri]);
                    }
                }
            }
        }
        usort($files, [
            $this,
            'compareFiles',
        ]);
        return $files;
    }
    
    /**
     * Compares two files based on size and file name.
     *
     * Callback for uasort() within \TestFileCreationTrait::getTestFiles().
     *
     * @param object $file1
     *   The first file.
     * @param object $file2
     *   The second class.
     *
     * @return int
     */
    protected function compareFiles($file1, $file2) {
        $compare_size = filesize($file1->uri) - filesize($file2->uri);
        if ($compare_size) {
            // Sort by file size.
            return $compare_size;
        }
        else {
            // The files were the same size, so sort alphabetically.
            return strnatcmp($file1->name, $file2->name);
        }
    }
    
    /**
     * Generates a test file.
     *
     * @param string $filename
     *   The name of the file, including the path. The suffix '.txt' is appended
     *   to the supplied file name and the file is put into the public:// files
     *   directory.
     * @param int $width
     *   The number of characters on one line.
     * @param int $lines
     *   The number of lines in the file.
     * @param string $type
     *   (optional) The type, one of:
     *   - text: The generated file contains random ASCII characters.
     *   - binary: The generated file contains random characters whose codes are
     *     in the range of 0 to 31.
     *   - binary-text: The generated file contains random sequence of '0' and '1'
     *     values.
     *
     * @return string
     *   The name of the file, including the path.
     */
    public static function generateFile($filename, $width, $lines, $type = 'binary-text') {
        $text = '';
        for ($i = 0; $i < $lines; $i++) {
            // Generate $width - 1 characters to leave space for the "\n" character.
            for ($j = 0; $j < $width - 1; $j++) {
                switch ($type) {
                    case 'text':
                        $text .= chr(rand(32, 126));
                        break;
                    case 'binary':
                        $text .= chr(rand(0, 31));
                        break;
                    case 'binary-text':
                    default:
                        $text .= rand(0, 1);
                        break;
                }
            }
            $text .= "\n";
        }
        // Create filename.
        $filename = 'public://' . $filename . '.txt';
        file_put_contents($filename, $text);
        return $filename;
    }

}