Yen currency is processed incorrectly (100x the input value)

This is a Stripe module bug. For some reason the gateway does this:

  /**
   * Formats the charge amount for stripe.
   *
   * @param integer $amount
   *   The amount being charged.
   *
   * @return integer
   *   The Stripe formatted amount.
   */
  protected function formatNumber($amount) {
    $amount = $amount * 100;
    $amount = number_format($amount, 0, '.', '');
    return $amount;
  }

Yeah.

$currency_storage = $this->entityTypeManager->getStorage('commerce_currency');
$currency = $currency_storage->load($amount->getCurrencyCode());
$fraction_digits = $currency->getFractionDigits();
if ($fraction_digits > 0) {
  $amount = $amount->multiply($fraction_digits);
}
return round($amount->getNumber(), 0);

This feels like something that should be easier (perhaps with a PaymentGatewayBase helper?). In any case, let's fix Stripe first.

We should be passing the entire Price object and getting both the number and currency code from there. No need to look at the payment.

Can you confirm that this works?

Added the helper to Commerce 2.2.
Update Commerce, and then test the attached patch.

Committed. Thank you for your work.