docs: ADR-0006 test-data builders, close out WP-70
Writes up the principle behind WP-70's three tracks ("build test data
through the same door production code uses") as ADR-0006, with a decision
table for which fixture idiom fits which test type. Updates the
test-strategy skill (adds the Fixtures rule, fixes its stale pre-monorepo
src/app/... worked-example paths) and the shared Storybook testing.mdx page
to match. Closes WP-70 with the signatures/counts as actually shipped.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
This commit is contained in:
Claude Sonnet 5
@@ -22,6 +22,13 @@ No `TestBed` for domain. Never assert on user-facing copy.
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only for wiring axe can't see.
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- **Never assert on `$localize` copy.** It changes per locale/edit — assert on the
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`Result`, the value object, or the message id.
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- **Fixtures go through the production door, never a hand-built literal** (ADR-0006).
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Replay real `Msg`s through the real `reduce` (`given(reduce, initial)(...msgs)`) for a
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state machine; `unwrapOk(parseX(raw))` for a value object; a type-state builder
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(`Given.Concept().Submitted()...`) for a backend aggregate with an ordered lifecycle.
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The one deliberate exception is a trust-boundary `parse*` spec, below — there the fixture
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must be a raw, possibly-malformed literal, because the test's whole point is "what if this
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shape is wrong." See ADR-0006's decision table for which idiom fits which test type.
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## Skeleton
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@@ -54,9 +61,13 @@ describe('parseThing', () => {
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## Worked examples
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- `src/app/registratie/domain/value-objects/postcode.spec.ts` — parser style.
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- `src/app/registratie/infrastructure/brp.adapter.spec.ts` — trust boundary (`null`/`{}`).
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- `src/app/registratie/domain/registratie-wizard.machine.spec.ts` — pure reducer.
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- `apps/ssp/src/app/registratie/domain/value-objects/postcode.spec.ts` — parser style.
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- `apps/ssp/src/app/registratie/infrastructure/brp.adapter.spec.ts` — trust boundary (`null`/`{}`).
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- `apps/ssp/src/app/registratie/domain/registratie-wizard.machine.spec.ts` — pure reducer.
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- `libs/shared/src/testing/{machine,remote-data,value-object}.ts` — the shared fixture
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helpers (ADR-0006); `apps/ssp/src/app/herregistratie/domain/intake.testing.ts` — a
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per-context wrapper (`givenIntake = given(reduce, initial)`); `intake.acceptance.spec.ts`
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— a full journey expressed as one replayed message sequence.
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## Verify
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@@ -120,6 +120,7 @@ for its existing violations, so every WP ends green.
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| [WP-67](WP-67-monorepo-behandelportal.md) | Merge behandelportal into this repo as a monorepo | 11 · Behandelportal | done |
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| [WP-68](WP-68-ddd-aggregate-hardening.md) | Aggregate invariants + status modelling (architecture review) | 12 · DDD hardening | done |
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| [WP-69](WP-69-intake-scholing-threshold-enforcement.md) | Enforce the scholing threshold server-side | 12 · DDD hardening | todo |
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| [WP-70](WP-70-test-data-builders.md) | Test-data builders: illegal fixtures unrepresentable (ADR-0006) | 12 · DDD hardening | done |
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Sequencing dependencies (stated in the WPs too): 01 before 10–15 (axe covers story churn);
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03/04 before 05–09 (boundaries stop new violations during refactors); 06 before 07 (typed
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@@ -0,0 +1,118 @@
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# WP-70 — Test-data builders: illegal fixtures unrepresentable
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Status: done
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Phase: 12 — DDD hardening
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## Why
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Decision #3 in `CLAUDE.md` — "make illegal states unrepresentable" — is honoured in
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production code (`AanvraagStatus`'s private-ctor/factory shape, the FE's tagged-union
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machines, branded value objects behind `parse*`) but **not** in the test suites that exercise
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them. Every layer independently reinvented ad-hoc, hand-built fixtures that reach around the
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production construction path:
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- Backend: `Aanvraag` is a mutable EF-backed bag with independent public setters. Its own
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`StatusAt` dereferences `Referentie!` three times on the unstated assumption
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"Submitted ⇒ Referentie != null" — a convention two test files (`RuleTests.cs`,
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`OpenZaakZaakSourceTests.cs`) kept consistent by hand across eight inline fixtures.
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- Frontend: no shared fixture helper existed anywhere. Every machine spec redefined its own
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throwaway literal helper (`editing1/2/3`, `editingWith`), each hardcoding fields like
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`errors: {}` — asserting against shapes the real reducer may never produce.
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- E2E: the seeded BSN and a diploma id were copy-pasted across all three specs, coupled to
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`SeedData.cs`'s exact shape by comment only.
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## Read first
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- ADR-0006 (`docs/reference/architecture/0006-test-data-builders.md`) — the principle and the
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full decision table this WP implements.
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- `CLAUDE.md` §"The decisions" #3, #5.
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- `backend/src/BigRegister.Api/Data/ApplicationStore.cs` (`Aanvraag`, `StatusAt`).
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- `backend/src/BigRegister.Api/Domain/Applications/AanvraagStatus.cs` — the exemplar this
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WP's backend builder mirrors.
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- `backend/src/BigRegister.Api/Domain/Beoordeling/BeoordelingRules.cs`.
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## Decisions (pre-made, don't relitigate)
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1. **No `With*`-per-field builders anywhere.** A builder that opens every field back up is an
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object literal with extra syntax — reject that shape on either side of the seam.
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2. **Backend: a type-state builder.** `Given.Concept()` → `ConceptAanvraag` (only `.AtStep`/
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`.Submitted`/`.Build` exist) → `SubmittedAanvraag` (only `.Decided`/`.Build` exist) →
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`DecidedAanvraag`. `Decided(...)` validates a toelichting by calling the real
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`BeoordelingRules.RequiresToelichting`, not by re-stating the rule.
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3. **`Aanvraag` itself stays mutable** — WP-68 deliberately kept it an EF-backed class; fixing
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that for real is an EF-mapping refactor, out of scope here (see Follow-ups).
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4. **Frontend: replay, don't fabricate.** One combinator, `given(reduce, initial)(...msgs)`
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(`libs/shared/src/testing/machine.ts`), replaces every hand-written state literal. Value
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objects: `unwrapOk(parseX(raw))`, never a cast. `RemoteData`: named constructors
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(`loading()`/`success(v)`/`failure(e)`), replacing duplicated per-file literals.
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5. **E2E stays a flat smoke suite** (WP-19's scope). Only extract shared `Actors`/`SeedRefs`/
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`loginAs` — no page-object layer, no Given/When/Then runner, no dev-only seeding API.
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The shared-mutable-backend isolation problem is a documented follow-up, not fixed here.
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6. **Convert worst offenders only**, not a full sweep: `RuleTests.cs`'s `Decided()` helper +
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`OpenZaakZaakSourceTests.cs`'s seven inline initializers (backend);
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`herregistratie.machine.spec.ts` + `change-request.machine.spec.ts` + both RemoteData
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specs (frontend); all three e2e specs (actors/seed-refs only).
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## Files
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| Area | Path |
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| ---------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
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| New (BE) | `backend/tests/BigRegister.Tests/Builders/AanvraagBuilder.cs`, `Acceptance/BesluitLifecycleTests.cs` |
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| Edit (BE) | `RuleTests.cs`, `OpenZaakZaakSourceTests.cs` |
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| New (FE) | `libs/shared/src/testing/{machine,remote-data,value-object}.ts`, `herregistratie/domain/intake.testing.ts`, `intake.acceptance.spec.ts` |
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| Edit (FE) | `herregistratie.machine.spec.ts`, `change-request.machine.spec.ts`, `remote-data.spec.ts`, `machine-remote-data.spec.ts`, both `tsconfig.app.json`, `angular.json` |
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| New (e2e) | `e2e/support/actors.ts` |
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| Edit (e2e) | `smoke.spec.ts`, `brief-v2.spec.ts`, `error-state.spec.ts` |
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| Docs | ADR-0006, `libs/shared/docs/testing.mdx`, `.claude/skills/test-strategy/SKILL.md`, this file + backlog README row |
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## Steps
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Executed as three file-disjoint parallel tracks (backend / frontend / e2e), each ending its
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own layer's tests green, then a combined gate, then docs written up against the interfaces as
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actually shipped.
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## Acceptance criteria
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- [x] `Given.Concept().Decided(...)` does not compile (proved live: temporarily inserted the
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call, confirmed `dotnet build` fails with `CS1061`, reverted).
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- [x] `Decided(Besluit.Afwijzen)`/`MeerInfoOpvragen` with no toelichting throws, via the real
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`BeoordelingRules.RequiresToelichting`.
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- [x] Backend tests: 220/220 passing (was 216 before; +4 from `BesluitLifecycleTests`).
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- [x] Frontend: `npm test` green across all four projects (ssp/behandelportal/shared/beheer);
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converted specs assert the same behaviour as before (diffed, not just re-passed) —
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one case (`editing3`'s hardcoded `errors: {}` at step 3 with invalid punten) was
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confirmed reachable via `SetField` after `Next`, not an unrepresentable state, so the
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assertion carried over unchanged.
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- [x] No fixture-only export (`givenIntake` etc.) leaks into a production bundle — confirmed
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via `grep -rl` on `dist/` after both a plain and a `--localize` build.
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- [x] `npm run ci` green (lint, format, tokens, both localized builds, audit, backend
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format+test, snippet-drift, api-client-drift).
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- [~] `npm run e2e` — refactor reviewed line-by-line (zero assertions changed), but not run to
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completion in this environment: port 4200 was occupied by an unrelated container
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(`team-monitor-web-1`), not this repo's stack. Confirm on a clean runner/CI before
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relying on it; not a regression introduced by this WP.
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## Verification
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```bash
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cd backend && dotnet format --verify-no-changes && dotnet test # 220/220
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npm run ci # green (2026-08-18)
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npm run e2e # run on a clean port 4200
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```
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## Out of scope
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- E2E test isolation (a dev-only seed endpoint) — the real fix for the shared-mutable-backend
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problem; a new production-adjacent surface needing its own security review.
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- Making `Aanvraag` itself illegal-states-unrepresentable (EF-mapping refactor).
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- `RegistrationStatus`'s equivalent flat-record gap (`Domain/Registrations/`) — same class of
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defect, separate WP.
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- E2E coverage for `apps/behandelportal` (currently zero).
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## Risks
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- The backend type-state builder only guards the fields it models (`Submitted`, `Referentie`,
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`SubmittedAt`, `BesluitStatus`, `BesluitToelichting`); other `Aanvraag` fields (e.g.
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`ZaakUrl`) are still set post-`.Build()` directly, since `Aanvraag` remains mutable. A
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future field added to the lifecycle needs a deliberate builder update, or it silently
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reopens the same gap this WP closed.
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@@ -0,0 +1,164 @@
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# ADR-0006 — Test data through the production door (builders, replay, and where each applies)
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Status: Accepted · Date: 2026-08-18
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## Context
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Decision #3 in `CLAUDE.md` is "make illegal states unrepresentable," and the production code
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mostly honours it: `AanvraagStatus` (backend) is a `sealed class` with a private constructor
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reachable only through five static factories; the frontend's wizards are tagged-union state
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machines driven by a pure `reduce`; form inputs are branded value objects reachable only
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through a `parse*` that returns `Result`.
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The test suites are the one place this invariant is not enforced — they build fixtures by
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hand instead of through those same doors:
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- **Backend.** `Aanvraag` (`Data/ApplicationStore.cs`) is a mutable EF-backed bag: `Submitted`,
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`Referentie`, `BesluitStatus`, `SubmittedAt` are independent public setters. Its own
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`StatusAt` dereferences `Referentie!` three times — "Submitted ⇒ Referentie != null" is
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convention, not type. Two test files (`RuleTests.cs`, `OpenZaakZaakSourceTests.cs`) kept
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eight such fixtures internally consistent by hand, each re-deciding for itself which fields
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a given scenario needs.
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- **Frontend.** No shared fixture helper existed anywhere in `apps/` or `libs/`. Every spec
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redefined its own throwaway literal function (`editing1/editing2/editing3`, `editingWith`,
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a local `ok()`), each hardcoding fields like `errors: {}` — asserting against a shape the
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real reducer may never actually produce, because the literal skips the reducer entirely.
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- **E2E.** The one seeded citizen's BSN and a diploma id were duplicated as bare string
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literals across every spec, coupled to `SeedData.cs`'s exact ordering by comment only, with
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no compiler check if the seed ever changed shape.
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A hand-rolled literal is not "faster test setup" — it is a second, unchecked implementation
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of the domain's construction rules, sitting right next to the real one.
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## Decision
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**Build test data through the same door production code uses. A test-data helper's job is to
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supply _defaults_, never to bypass _invariants_.**
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Concretely: reject any test helper shaped as a field-by-field builder (`.withX().withY()...`
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over an otherwise-open constructor) — that is an object literal with extra syntax, and it
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re-opens every illegal state the production type closed. Each layer instead gets the
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narrowest helper that **cannot** construct an illegal instance, because it has no path to one.
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### 1. Backend aggregates with a lifecycle → a type-state builder
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Where a production type enforces its invariants (or should), the test builder mirrors that
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enforcement as separate **types per stage**, so an illegal call is a compile error, not a
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runtime surprise:
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```csharp
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Given.Concept() // ConceptAanvraag — only .Submitted() or .Build() exist
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.Submitted() // SubmittedAanvraag — only .Decided() or .Build() exist
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.Decided(Besluit.Afwijzen, "reden"); // DecidedAanvraag
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```
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`Given.Concept().Decided(...)` does not compile — `Decided` is simply not a member of
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`ConceptAanvraag`. Where the production rule is more subtle than "which methods exist"
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(e.g. "Afwijzen requires a toelichting"), the builder **calls the real production rule**
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(`BeoordelingRules.RequiresToelichting`) rather than re-stating it — this is what keeps the
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builder from drifting out of sync with the domain as the domain changes.
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Use this shape whenever a production aggregate has an ordered lifecycle and either (a)
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already guards it with factories (mirror them 1:1), or (b) doesn't yet guard it (as with
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`Aanvraag` itself, see Consequences) — the test-only builder is not a substitute for fixing
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the production type, but it stops the test suite from being the place the ungated shape leaks
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out into assertions.
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### 2. Frontend state machines → replay real messages through the real reducer
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No object is built directly. A fixture is the result of running real `Msg`s through the real
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`reduce`:
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```ts
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export const given =
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<S, M>(reduce: (s: S, m: M) => S, initial: S) =>
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(...msgs: M[]): S =>
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msgs.reduce(reduce, initial);
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export const givenIntake = given(reduce, initial); // per-context wrapper, pure TS
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```
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There is no way to hand-write a `Submitting` state whose draft contradicts its step, or to
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assert `errors: {}` into existence — the only states reachable are the ones the reducer can
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actually produce, because production is the only code path that produces them.
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### 3. Value objects → `unwrapOk`, never a cast
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A test that needs a valid branded value calls the real `parse*` and unwraps it:
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```ts
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export const unwrapOk = <E, T>(r: Result<E, T>): T => {
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if (!r.ok) throw new Error('unwrapOk: parser rejected the input');
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return r.value;
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};
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const postcode = unwrapOk(parsePostcode('1234 AB'));
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```
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This closes the `'garbage' as Postcode` route — a spec can only ever hold a value the real
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parser accepted.
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### 4. RemoteData → named constructors, not ad-hoc literals
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`loading()` / `success(v)` / `failure(e)` in `libs/shared/src/testing/remote-data.ts` replace
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the per-spec local `ok()`/`loading`/`failure` literals. `RemoteData` has no invariant to
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protect (it's a plain closed union with no smart constructor in production either), so this
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one is about **removing duplication**, not closing an illegal-state gap — named constructors
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belong here because they are shorter and consistent, not because the literal was unsafe.
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### 5. E2E — shared actors/seed-refs, not a DSL
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E2E fixtures are named, not built: `Actors.zorgverlener`, `SeedRefs.diplomaZonderPolicyVragen`
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in `e2e/support/actors.ts`, with `loginAs(page, actor)` replacing the duplicated login
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sequence. No page-object layer, no Given/When/Then runner — Playwright specs stay flat
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`page.getByRole` sequences (matching WP-19's "smoke, not full coverage" scope), the only
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change is that the values they use have one source instead of N copies. See "Where this does
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**not** reach" below for why the deeper e2e problem is out of scope here.
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## Decision table — what to reach for, by test type
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| Test type | Where it lives | Fixture idiom | Do **not** |
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| -------------------------------------------------------- | ------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------- |
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| Domain aggregate with a guarded lifecycle (backend) | `*.Tests/Builders/` | Type-state builder mirroring the production factories; delegate any non-trivial rule to the real rule class | A field-by-field `.WithX()` builder, or an object initializer with all fields public |
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| Pure reducer / state machine (frontend) | `domain/*.testing.ts` | `given(reduce, initial)(...msgs)` — replay real messages | A literal returning `{ tag: 'Editing', ... }` by hand |
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| Value object / parser | co-located with the parser's spec | `unwrapOk(parseX(raw))` | `'x' as BrandedType` |
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| Plain closed union with no invariant (e.g. `RemoteData`) | `libs/shared/src/testing/` | Named one-line constructors (`loading()`, `success(v)`) | Redefining the same literal per spec file |
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| Trust-boundary `parse*` (adapter) | co-located, per `test-strategy` skill | Hand-written DTO literals **are** correct here — the point of the test is "what if the untrusted shape is wrong," so the fixture must be a raw, possibly-malformed literal, not a validated domain value | Routing malformed-input tests through a builder that can't express malformed shapes |
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| UI component | Storybook story + axe | Args as `input()`s on the component; no fixture builder needed | A component test with a hand-built store/model |
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| Acceptance / behaviour test (either side) | `Acceptance/*Tests.cs` (backend), `*.acceptance.spec.ts` (frontend) | The same builder/replay idiom as above, composed into one Given→When→Then read | A separate BDD/Gherkin runner — the language's own test framework plus the builder is enough |
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| E2E | `e2e/support/` | Named actor/seed-ref constants + a thin `loginAs`-style setup helper | A page-object framework or DSL — out of proportion to a 3-spec smoke suite |
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The common thread: **the fixture idiom is only ever a thinner or safer path to the same
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construction the domain already performs** — never a parallel, unchecked one. The trust-
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boundary row is the deliberate exception, not a contradiction: there the entire point of the
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test is to exercise what happens when the input _isn't_ valid, so the fixture must be able to
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represent the invalid shape a builder would refuse to construct.
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## Consequences
|
||||
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- **+** An illegal backend fixture (e.g. a decided-but-not-submitted `Aanvraag`) is now a
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compile error in the builder path, not a silent bad test.
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- **+** Frontend specs can no longer assert against a state the reducer cannot actually reach;
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a hardcoded `errors: {}` fixture literal can't drift from what validation actually produces.
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- **+** One seeded identity/diploma reference in e2e instead of N copies — a reseed shows up as
|
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one changed constant, not a hunt through three spec files.
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- **−** `Aanvraag` itself is **not** made illegal-states-unrepresentable by this ADR — it
|
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remains a mutable EF-backed class (WP-68 kept it that way deliberately; `ApplicationStore`
|
||||
is its only production writer). The builder is a test-only enforcement layer sitting in
|
||||
front of a production type that still allows the bad shape directly. Closing that gap for
|
||||
real means an EF-mapping change, tracked as a follow-up, not done here.
|
||||
- **−** A type-state builder is more ceremony than a constructor call for a one-off fixture.
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||||
Reach for it only where a lifecycle actually has ordered stages worth protecting — a flat
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||||
value type doesn't need one (see the `RemoteData` row above).
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## Where this does **not** reach (deliberately out of scope)
|
||||
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||||
- **E2E test isolation.** The three Playwright specs share one mutable backend and admit it in
|
||||
their own comments ("restart the backend between CI runs"). The real fix is a dev-only seed
|
||||
endpoint each test can call to build its own isolated citizen/aanvraag — a new
|
||||
production-adjacent surface that needs its own security review, not a fixture-idiom change.
|
||||
Tracked as a follow-up; not fixed here.
|
||||
- **`RegistrationStatus`** (`Domain/Registrations/`) has the same class of gap as `Aanvraag` —
|
||||
a flat record with four always-present nullable fields, whose own doc-comment says only one
|
||||
tag ever uses the deadline field — but is out of this ADR's scope (a separate WP).
|
||||
- **`apps/behandelportal` e2e coverage** is currently zero; adding it is a coverage gap, not a
|
||||
fixture-idiom question, and is a separate follow-up.
|
||||
@@ -63,9 +63,38 @@ expect(parseBrpAddress(null).ok).toBe(false);
|
||||
expect(parseBrpAddress({}).ok).toBe(false); // missing required field
|
||||
```
|
||||
|
||||
Elm-style machines test the pure `reduce` with inline state fixtures — no Angular
|
||||
Elm-style machines test the pure `reduce` — no Angular
|
||||
(`registratie/domain/registratie-wizard.machine.spec.ts`).
|
||||
|
||||
## Fixtures: build test data through the production door
|
||||
|
||||
A fixture is not a shortcut around the domain — it's the domain's own construction path, run
|
||||
once for the test. [ADR-0006](../../../docs/reference/architecture/0006-test-data-builders.md)
|
||||
covers this in full (with a backend example too); the frontend idiom is one combinator,
|
||||
`given` (`libs/shared/src/testing/machine.ts`):
|
||||
|
||||
```ts
|
||||
export const given =
|
||||
<S, M>(reduce: (s: S, m: M) => S, initial: S) =>
|
||||
(...msgs: M[]): S =>
|
||||
msgs.reduce(reduce, initial);
|
||||
|
||||
export const givenIntake = given(reduce, initial); // per-context wrapper, pure TS
|
||||
```
|
||||
|
||||
A machine spec replays real `Msg`s instead of hand-writing a `State` literal — so a fixture
|
||||
can only ever be a state the real reducer actually produces:
|
||||
|
||||
```ts
|
||||
const atStep3 = givenIntake(Start(), SetUren('1200'), Next(), SetDiplomaHerkomst('NL'), Next());
|
||||
```
|
||||
|
||||
The same rule extends to value objects (`unwrapOk(parseX(raw))` instead of a cast) and to
|
||||
`RemoteData` (`loading()` / `success(v)` / `failure(e)` in
|
||||
`libs/shared/src/testing/{value-object,remote-data}.ts` instead of a redefined-per-file
|
||||
literal). **Never** a `.withX().withY()` builder over an open constructor — that just
|
||||
re-opens whatever illegal state the domain closed.
|
||||
|
||||
## UI = Storybook, not heavy component tests
|
||||
|
||||
`@storybook/addon-a11y` runs the `wcag2a/2aa/21a/21aa` rule sets on **every** story;
|
||||
|
||||
Reference in New Issue
Block a user