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Testing

:::info Source Sourced from services/billing-service/TESTING_STRATEGY.md in the documentation repo. :::

1. Coverage Targets​

Domain 95% / 98% branch / 80% mutation. Integration 85%.

2. Unit Tests​

  • Invoice total computation (currency rounding, tax stacking).
  • Subscription state machine.
  • Dunning stage advancement (time-based).
  • Refund invariants (amount ≤ refundable).
  • Tax line calculation across jurisdictions.
  • Payout amount computation (revenue share, refund deductions).
  • Money arithmetic (micro-units; no floats).

3. Integration Tests (Testcontainers)​

  • Postgres + NATS + Stripe test mode.
  • Full payment flow: intent → confirm → webhook → event emitted.
  • Subscription renewal batch.
  • Refund flow.
  • Webhook signature validation (valid + invalid + replay).

4. Contract Tests​

Pact:

  • billing ← marketplace: order.placed.v1 → create intent.
  • billing → marketplace: payment.succeeded.v1, .failed.v1.
  • billing → notification: receipts, dunning messages.
  • billing → analytics: revenue events.
  • OpenAPI diff in CI.

5. Stripe Mock​

  • Use Stripe test mode in CI.
  • Stripe Mock server for fully offline tests.
  • Scenario scripts: successful payments, decline, 3DS required, disputed.

6. E2E Tests​

  • J-06: purchase → payment → license → enrollment.
  • J-17: subscription signup → trial → convert → renewal → cancel.
  • J-19: payment fail → dunning → resolve via new card.
  • J-20: refund → license revoked.

7. Load Tests​

  • 10k payment intents/min.
  • 1k webhooks/sec incoming (Stripe can batch).
  • Monthly renewal batch: 100k subscriptions.

8. Chaos​

  • Stripe outage simulation → retries + alert.
  • Webhook delivery delayed 30 min → replay still works.
  • Reconciliation catches injected drift.
  • Double webhook event → single side-effect.

9. Tax Tests​

  • Jurisdiction fixtures: US (per state), EU (VAT), Canada (GST/HST/PST), India (GST), UAE (VAT), UK (VAT post-Brexit).
  • Digital goods tax rules per jurisdiction.
  • Reverse-charge VAT for B2B EU.

10. PCI Tests​

  • No PAN in any log (CI grep for card patterns).
  • Tokenization flow tested end-to-end.
  • Annual PCI SAQ-A self-assessment.

11. Fraud Tests​

  • Simulated fraudulent patterns → flagged.
  • 3DS challenge flow.
  • Velocity limit triggers.

12. GDPR Tests​

  • Erasure saga: anonymize customer but retain billing records.
  • Data export for subject access request.

13. Reconciliation Tests​

  • Inject drift between our ledger and Stripe mock → reconciliation detects.
  • Monthly tax export fixtures.

14. CI Gates​

  • Unit + integration + contract green.
  • Stripe mock flows green.
  • OpenAPI + Pact verified.
  • PCI scope test (no PAN in logs).
  • Two-tenant iso green.
  • Mutation ≥ 80%.