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nettax.sx — alternative to quote.sx's gross-tax default: cart-quote-net taxes the net (post-discount) base. allocate-discount spreads the basket discount across lines by extended-price share with a deterministic largest-remainder pass so per-line shares sum exactly to the discount; each line taxed on its net at its class rate. Both policies reproducible; pick per jurisdiction. Total 239/239 across 15 suites. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
93 lines
2.2 KiB
Plaintext
93 lines
2.2 KiB
Plaintext
;; lib/commerce/tests/nettax.sx — discount-aware (net) tax policy.
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;; Uses (commerce-test name got expected) provided by conformance.sh.
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(define
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pcat
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(make-catalog
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(list
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(list "widget" 1000 :standard)
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(list "tea" 1000 :reduced))
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(list)
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(list)))
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(define
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rules
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(list
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(list :uk :standard :guest 2000)
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(list :uk :reduced :guest 500)))
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(define gctx (make-pricing-context pcat rules :uk :guest))
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;; widget x3 = 3000 (standard), tea x6 = 6000 (reduced); subtotal 9000
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(define
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cart
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(list (list "widget" :none 3) (list "tea" :none 6)))
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(define ruleset (list (list :percent "TEN" :standard 1000)))
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;; --- allocation: proportional, sums exactly to the discount ---
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(commerce-test
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"allocate-even"
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(allocate-discount pcat cart 300)
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(list 100 200))
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(commerce-test
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"allocate-sums-to-discount"
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(ct-sum (allocate-discount pcat cart 300))
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300)
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;; remainder distribution: 100 over (3000,6000)/9000 = (33,66) rem 1 -> (34,66)
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(commerce-test
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"allocate-remainder"
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(allocate-discount pcat cart 100)
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(list 34 66))
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(commerce-test
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"allocate-remainder-sums"
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(ct-sum (allocate-discount pcat cart 100))
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100)
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(commerce-test
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"allocate-zero"
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(allocate-discount pcat cart 0)
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(list 0 0))
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(commerce-test
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"allocate-empty"
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(allocate-discount pcat empty-cart 0)
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(list))
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;; --- net tax vs gross tax ---
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;; discount = TEN 10% of standard 3000 = 300, allocated (100 200).
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;; net: widget 2900@20%=580, tea 5800@5%=290 -> net tax 870 (gross was 900).
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(commerce-test
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"net-quote"
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(cart-quote-net gctx cart ruleset (list))
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{:codes (list "TEN") :subtotal 9000 :discount 300 :total 9570 :tax 870})
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;; same cart through the gross policy taxes 900 (the documented default)
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(commerce-test
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"gross-quote-for-contrast"
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(quote-tax (cart-quote gctx cart ruleset (list)))
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900)
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(commerce-test
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"net-tax-lower"
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(quote-tax (cart-quote-net gctx cart ruleset (list)))
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870)
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;; --- no discount: net policy == gross policy ---
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(commerce-test
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"no-discount-net-equals-gross"
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(=
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(cart-quote-net gctx cart (list) (list))
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(cart-quote gctx cart (list) (list)))
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true)
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;; --- empty cart ---
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(commerce-test
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"net-empty"
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(cart-quote-net gctx empty-cart ruleset (list))
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{:codes (list) :subtotal 0 :discount 0 :total 0 :tax 0})
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