public function write(string $fileName) : void
    {
        file_put_contents(
            $fileName,
            // str_replace here is to convert empty arrays into empty JS objects, which is expected by
            // codecov.io. Owner of the service said he was going to patch it, haven't tested since
            // Note: Can't use JSON_FORCE_OBJECT here as we **do** want arrays for the 'b' structure
            // which FORCE_OBJECT turns into objects, breaking at least the Istanbul coverage reporter
            str_replace('[]', '{}', (string) json_encode($this->coverage, JSON_UNESCAPED_SLASHES))
        );
    }