lib/Assertion.php
function match(string $pattern): self {
    return $this->expect($this->target, matchesRegularExpression($pattern));
  }
function match(string $pattern): self {
    return $this->expect($this->target, matchesRegularExpression($pattern));
  }
Reports an error if the target does not match the specified regular expression.
@param string $pattern The regular expression to test.
@return self This instance.