Add currencyCode support to initPaymentSheet for Google Pay & Setup Intents

[brendanm-stripe]

Necessary to support Setup Intents including Google Pay

const { error } = await initPaymentSheet({
      customerId: customer,
      customerEphemeralKeySecret: ephemeralKey,
      setupIntentClientSecret: setupIntentClientSecret,
      customFlow: false,
      merchantDisplayName: 'Example Inc.',
      applePay: true,
      merchantCountryCode: 'US',
      currencyCode: 'USD', // this is required for setup intents
      style: 'automatic',
      googlePay: true,
      testEnv: true,
      primaryButtonColor: '#635BFF', // Blurple
      returnURL: 'stripe-example://stripe-redirect',
      defaultBillingDetails: billingDetails,
      allowsDelayedPaymentMethods: true,
    });

[brnunes-stripe]

This fix is correct.
Google Pay requires a currency code and Setup Intents don't have that field, so we need the user to tell us in the Google Pay configuration.
I'm not familiar with the React codebase, but it would be good to document that somewhere, similar to how we do on the Android SDK.

[brendanm-stripe]

While there is not currently an example screen for Payment Sheet + Setup Intent, the non-Payment Sheet Google Pay docs do mention this currencyCode requirement:
https://github.com/stripe/stripe-react-native/blob/master/docs/GooglePay.md#present-google-pay-sheet

and this is also noted in the Android SDK docs: https://stripe.com/docs/payments/save-and-reuse?platform=android&ui=payment-sheet#add-google-pay

In parallel to this PR, I've got a draft of changed to add this to the RN docs here: https://stripe.com/docs/payments/save-and-reuse?platform=react-native&ui=payment-sheet#add-google-pay

[julestruong]

Hey guyz, thx a lot for this PR this could save my day.
Any update on the ETA ?

[charliecruzan-stripe]

thanks for this fix 🙏 just one small question

[brendanm-stripe]

Docs updated here: https://stripe.com/docs/payments/save-and-reuse?platform=react-native&ui=payment-sheet#react-native-google-pay

const { error, paymentOption } = await initPaymentSheet({
  // ...
  googlePay: true,
  merchantCountryCode: 'US',
  currencyCode: 'USD', // currency must be specified for setup mode
  testEnv: true, // use test environment
});