[thomasluizon]

Fixes thomasluizon/orbit-tickets#1581

An unused 10% referral coupon now makes billedAmountPerPeriod 900 on a 1000-unit subscription. After consumption it returns to 1000, while amountPerPeriod remains the plan price.

src/Orbit.Infrastructure/Services/StripeBillingService.cs requests preview_mode=next so Stripe includes applicable one-time coupons. The existing filter still sums only non-prorated lines for the requested subscription, subtracts Stripe's line discounts, excludes one-time charges and customer balance, and returns null when a preview is unavailable or incomplete. The optional response field and its type are unchanged.

tests/Orbit.Infrastructure.Tests/Services/StripeBillingDetailsTests.cs covers once and forever coupons using the referral percentage from AppConstants, coupon consumption, no coupon, and customer credit and debit balances. Existing proration, one-time item, other-subscription, and unavailable-preview cases remain. The coupon fixture varies its response with preview mode, so it cannot give a one-time discount to a recurring preview.

External interface evidence

Read Stripe.net source at commit f4f1c8ce704825d7d7f00b4c9d848a2d028757eb, identified by the installed Stripe.net 52.4.2 package's stripe.net.nuspec repository entry. Reproduce by inspecting that package entry and opening these pinned source files:

• InvoiceCreatePreviewOptions.cs:111-118 declares PreviewMode, accepts next and recurring, and documents the next default. Lines 58-67 confirm inherited discounts; lines 136-153 confirm Subscription and SubscriptionDetails.
• InvoiceLineItem.cs:43-64 confirms Currency and DiscountAmounts; lines 135-140 confirm Parent; lines 207-213 define Subtotal before discounts and taxes.
• InvoiceLineItemParent.cs:18-23 confirms SubscriptionItemDetails; InvoiceLineItemParentSubscriptionItemDetails.cs:18-37 confirms Proration and Subscription.
• InvoiceLineItemDiscountAmount.cs:11-16 confirms the discount Amount in minor currency units. Invoice.cs:116-126 explains customer balance in AmountDue; lines 664-672 define Lines, and lines 837-844 define StartingBalance. StripeList.cs:19-33 confirms Data and HasMore.
• Coupon.cs:84-91 confirms coupon durations. Orbit's producer uses Duration = "once" in StripeCouponRewardService.cs:31-40 and the 10% constant in AppConstants.cs:29.
• Stripe's preview API reference confirms that recurring previews include only repeating or forever coupons, while next previews include applicable one-time items. The fixture follows that distinction.

Test evidence

Before editing the test or implementation:

dotnet test tests/Orbit.Infrastructure.Tests --filter FullyQualifiedName~Handle_ReferralDiscountChangesRecurringAmountWithoutChangingPlanPrice --logger 'console;verbosity=minimal'

Exit 0, 1 passed with the defect present. The original forever-only fixture missed the defect.

After strengthening the tests, with the implementation still using recurring mode:

dotnet test tests/Orbit.Infrastructure.Tests --filter FullyQualifiedName~StripeBillingDetailsTests --logger 'console;verbosity=minimal'

Exit 1, 3 failed and 24 passed. Handle_ReferralDiscountChangesRecurringAmountWithoutChangingPlanPrice(duration: "once") and Handle_ConsumedReferralCouponRestoresNormalBilledAmount expected 900 but received 1000. The forever case also rejected the recurring request mode. After changing the implementation to next mode, the same command exited 0 with all 27 passing.

Verification after the commit:

• dotnet build Orbit.slnx: exit 0, zero errors. Existing dependency and obsolete API warnings remain. OpenAPI regeneration produced no tracked changes.
• dotnet test tests/Orbit.Infrastructure.Tests --no-build --filter FullyQualifiedName~StripeBillingDetailsTests: exit 0, 27 passed.
• dotnet test tests/Orbit.Domain.Tests --no-build: exit 0, 789 passed.
• dotnet test tests/Orbit.Application.Tests --no-build: exit 0, 5313 passed.
• dotnet test tests/Orbit.Infrastructure.Tests --no-build: exit 0, 3853 passed.
• dotnet test Orbit.slnx --no-build: exit 0, all 9995 tests passed across the four test projects, including 40 analyzer tests.
• Commit hooks passed formatting, dash, timeless text, root allowlist, and suppression checks.

[pullfrog]

✅ No new issues found.

Reviewed changes Reviewed the complete billing-preview change and regression tests, verified Stripe's documented preview semantics, and checked the consumer schema; all 27 focused billing tests passed.

• One-time coupon preview: Uses preview_mode=next so applicable one-time referral coupons affect BilledAmountPerPeriod, while preserving the plan price and existing subscription-line exclusions.
• Regression coverage: Exercises once and forever coupons, restoration after coupon consumption, and independence from customer credit or debit balances, alongside the existing filtering and unavailable-preview cases.

Validation used mocked Stripe clients, not a live Stripe request.

  ^{｜ View workflow run ｜ Using gpt-6.1-sol ｜ 𝕏}

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud