Captures the decision to add @repo/core-testing, factories, contract suites, vitest safety defaults, coverage thresholds, Storybook test-runner, and CI as one cohesive TDD foundation. Per-feature AGENTS.md gains a Tests section pointing to factories, contract suite, and the canonical test commands. Spec: §7.4, §7.5 Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2.8 KiB
ADR-011: TDD Foundation
Status: Accepted Date: 2026-05-05 Supersedes: none Spec: docs/superpowers/specs/2026-05-05-tdd-foundation-design.md
Context
The vertical-feature monorepo refactor (ADRs 001-010) established clean architecture with per-feature DI containers but did not enforce TDD as the path of least resistance. Agentic workers were producing code-first commits with tests added later, leading to test theatre and mock/real drift.
Decision
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New package
@repo/core-testing(tag: tooling) — shared test utilities: defineFactory, defineContractSuite, renderWithProviders, mock-payload helpers, jsdom setup file. Taggedtoolingso any package may depend on it as devDependency without boundary violation. -
Vitest base configs split into node + jsdom with safety defaults (clearMocks, restoreMocks, mockReset, unstubGlobals, sequence.shuffle) and coverage thresholds (80/75/80/80 baseline; 100% in entities + use-cases + controllers).
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Factories per feature in
src/__factories__/replace inline fixtures. Stable date defaults (2026-01-01) so snapshot diffs reflect SUT behavior only. -
Contract suites per repository interface in
src/__contracts__/run against every implementation (Mock + Payload). Eliminates the class of bug where the mock and the real impl drift apart. -
Tests in core- packages and apps* — composition smoke tests (appRouter, payloadConfig, bind-production, providers).
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Storybook test-runner — every story executed as a smoke test.
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CI workflow — typecheck + lint + boundaries + test + build + e2e + storybook on every PR. Coverage uploaded as artifact.
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Two new docs — tdd-workflow.md (process) + restructured adding-a-feature.md (interleaves tests with impl).
Alternatives considered
- Fixture files instead of factories — rejected. Fixtures rot with schema changes and require manual updates per test.
- One shared test file per impl — rejected. Contract suites give the same coverage in fewer LOC and prevent drift.
- Real Postgres in tests via testcontainers — rejected for unit tests (slow, complex). Repository contract suites + vi.mock('payload') give equivalent confidence in milliseconds.
- Stryker mutation testing — deferred. Coverage thresholds + contract suites get us most of the way; mutation testing is incremental.
Consequences
- New package to maintain (small, mostly stable surface).
- Coverage thresholds may fail builds initially; we add tests to cross threshold as part of Plan 7.
- Sequence shuffle may surface latent flakes; we fix as found.
- Templates for new features now require writing tests first; this is by design.
Refines
- ADR-006 (boundary tags) — adds @repo/core-testing as a tooling package.