code: public function register() {
  		$targets = Tokens::$textStringTokens;
  
  		// Add CSS style target.
  		$targets[] = \T_STYLE;
  
  		// Set the target selectors regex only once.
  		$selectors = array_map(
  			'preg_quote',
  			$this->target_css_selectors,
  			array_fill( 0, \count( $this->target_css_selectors ), '`' )
  		);
  		// Parse the selectors array into the regex string.
  		$this->target_css_selectors_regex = sprintf( $this->target_css_selectors_regex, implode( '|', $selectors ) );
  
  		// Add function call targets.
  		$parent = parent::register();
  		if ( ! empty( $parent ) ) {
  			$targets[] = \T_STRING;
  		}
  
  		return $targets;
  	}
docs: Returns an array of tokens this test wants to listen for.
  
  @return array