IdempotencyKey::forPrice()/forProduct() built the parameter array they
fingerprint, and FakeStripeClient::createPrice()/createProduct() rebuilt the
identical array literal by hand purely to feed replay()/rememberKey(). Nothing
tied those two literals together — a later change to what a Price call
fingerprints could drift from what the fake checks for a collision, and no
test would catch it, because the HttpStripeClient tests exercise forPrice()
alone and the FakeStripeClient tests exercise its own local array alone.
priceParameters()/productParameters() are now the one answer to "what counts
as the same call"; forPrice()/forProduct() and the fake both ask it instead of
each keeping their own copy. Fingerprint and key format are unchanged — this
is the duplication coming out, not new behaviour. refund(),
cancelSubscription(), addSubscriptionItem() and createCheckoutSession() are
untouched: their local parameter arrays are the fake's own record of the call,
never fingerprinted into a key, so there was nothing to duplicate there.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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