> Somebody will have said at some point "we should actually have the tests charge money" and somebody else will have said "well we can't have the tests actually charge money, that's a legal/accounting problem, it might even be a crime" and then nobody would have asked what the next best thing was.
If you support multicurrency billing, then have the tests bill a test customer in XTS (ISO 4217 code for test currency).
Now I’m picturing the 3am end of quarter fire drill in finance when they discover the company has accounts receivable of fourteen billion $XTS and it’s appearing in the quarterlies.
So how is it a "foot gun" to add XTS as an additional currency, for internal use only?
I presume AWS sets its prices in USD, and then converts them to the other currencies using the relevant exchange rate - the services themselves don't know about UAE dirham, but the billing system does. So XTS just becomes another exchange rate. You could even fix it as 1 XTS = 1 USD, although choosing a different exchange rate than parity is likely to surface more bugs.
I'm saying, the conversion to (any) currency needs to be done downstream of the service (to a general billing service). The service needs to bill "credits".
> presume AWS sets its prices in USD, and then converts them to the other currencies using the relevant exchange rate
When talking about e2e tests, it matters where the e's are. If they are at the public interface of "the service", then, indeed, you'd test against "credits".
But ideally, there'd be e2e tests that test the consumers' experience, where the 'e's are the web interface, emails, CLI and other things consumers click on, read, enter etc. This is where a "test currency" makes sense.
You can have your billing service billing in the test currency for e2e (and probably with a value that does not match the USD) so you can test "ok this should cost 1 credit so in the end I should have 18 $currency"
If you support multicurrency billing, then have the tests bill a test customer in XTS (ISO 4217 code for test currency).