Add new fields to lastResponse: apiVersion, stripeAccount, idempotencyKey

[polybuildr]

r? @jlomas-stripe
cc @stripe/api-libraries @brandur-stripe

If any of these three fields are set in the headers, copy them over to lastResponse as suggested in #406.
Also add tests for the new fields and refactor an existing test for lastResponse.

[richardm-stripe]

Hi @polybuildr -- thanks for the contribution!

This looks good. One request: can we avoid adding the new dev dependency on uuid in the test? Hardcoding an identifier would be better.

[polybuildr]

Hi @richardm-stripe! I'm glad you brought that up! I started with hardcoding the key but then came across a problem. The test isn't hermetic and actually communicates with the Stripe API, so if I hardcode an idempotency key, running the test twice gives me an error saying: No such customer: cus_HdkOjCApDMTkzx.

I'm not sure why it's that error specifically -- I didn't investigate. I can look into it later if you don't already know off the top of your head.

[richardm-stripe]

Ah thanks @polybuildr, I forgot about that. Can we roll our own random identifier instead of introducing a dependency?
(Math.random() * Number.MAX_SAFE_INTEGER).toString(16) or something?

[polybuildr]

Ah yes, that's a reasonably good solution. I'll update to include a random identifier without using a dependency. :)

[polybuildr]

Done! I know it doesn't matter, but I was still uncomfortable using Math.random so I used the Node crypto module's randomBytes. No additional dependencies, so that should still be okay. :)

[richardm-stripe]

Thank you, this looks great. We are very excited about and appreciative of the contributions you are making to this repo & stripe-cli!

[richardm-stripe]

Released in 8.74.0

[polybuildr]

Thanks for the review! Glad to be of help. :)