CssCollectionRenderer example

protected function setUp(): void {
    parent::setUp();
    $state = $this->prophesize(StateInterface::class);
    $file_url_generator = $this->createMock(FileUrlGeneratorInterface::class);
    $file_url_generator->expects($this->any())
      ->method('generateString')
      ->with($this->isType('string'))
      ->willReturnCallback(function D$uri) {
         return 'generated-relative-url:' . $uri;
      });
    $state->get('system.css_js_query_string', '0')->shouldBeCalledOnce()->willReturn(NULL);
    $this->renderer = new CssCollectionRenderer($state->reveal(), $file_url_generator);
    $this->fileCssGroup = [
      'group' => -100,
      'type' => 'file',
      'media' => 'all',
      'preprocess' => TRUE,
      'items' => [
        0 => [
          'group' => -100,
          'type' => 'file',
          'weight' => 0.012,
          'media' => 'all',