/**
  * @covers ::__toString
  * @covers ::jsonSerialize
  */
 public function testToString()
 {
     $string = 'Can I please have a @replacement';
     $formattable_string = new FormattableMarkup($string, ['@replacement' => 'kitten']);
     $text = (string) $formattable_string;
     $this->assertEquals('Can I please have a kitten', $text);
     $text = $formattable_string->jsonSerialize();
     $this->assertEquals('Can I please have a kitten', $text);
 }