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happier-testing

Testing & Quality
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Repo-specific TDD and test-validation workflow for Happier changes, with lane selection, fixture policy, and anti-flake guardrails.

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Source SKILL.md: https://github.com/happier-dev/happier/blob/HEAD/skills/happier-testing/SKILL.md

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Happier Testing And TDD

Use this skill for behavior-changing work in this repository, especially when changes touch shared runtime contracts, CLI/server/UI flows, or any lane that historically accumulates stale fixtures.

Goal

Apply strict RED-GREEN-REFACTOR while following Happier-specific lane, fixture, and rerun rules so changes do not silently drift until a late pipeline sweep.

Workflow

  1. Inventory first
  • Search for existing tests by symbol, route, command, feature id, config key, component name, or error code.
  • Map the affected lane(s) and any shared/package-local harnesses the change can invalidate before editing code.
  • Update the most relevant existing test first when possible.
  • Consolidate overlapping tests instead of stacking new ones on top.
  1. Classify failures correctly
  • production bug: runtime behavior is wrong
  • test drift: assertions/fixtures assume an obsolete contract
  • harness drift: helpers/mocks/testkit no longer match real runtime wiring
  • infra/resource issue: disk, Docker, stale child processes, or similar environment failures
  1. RED
  • Write or update the smallest relevant test first.
  • Run only the smallest relevant slice and confirm it fails for the expected reason.
  1. GREEN
  • Implement the smallest fix that satisfies the failing behavior.
  • Keep internal behavior real; mock only system boundaries.
  1. REFACTOR
  • Extract shared helpers only when there is repeated real duplication or repeated stale drift.
  • Keep file responsibilities focused.
  1. Broaden validation
  • After a targeted green run in a shared area, rerun one broader related lane.
  • Before handoff, rerun the touched package typecheck/build-enforcing lane and the relevant repo lanes.

Happier Lane Map

Canonical top-level lanes:

  • yarn test
  • yarn test:integration
  • yarn test:e2e:core:fast
  • yarn test:e2e:core:slow
  • yarn test:e2e:ui
  • yarn test:providers
  • yarn test:db-contract:docker

CLI lane rule:

  • apps/cli unit tests must not force a full CLI dist build.
  • Use the lane-specific global setup files:
    • src/test-setup.unit.ts
    • src/test-setup.integration.ts
    • src/test-setup.slow.ts

Fixture And Mock Policy

  • Do not partially mock central shared modules such as @/sync/domains/state/storage.
  • Prefer package-local shared factories/testkits for repeated boundary mocks.
  • Keep cross-repo primitives in packages/tests/src/testkit.
  • Before adding a new helper or mock family, inspect the codebase for the existing canonical testkit/helper for that boundary.
  • Prefer reusing, extending, generalizing, or extracting from canonical helpers over introducing similar-but-different variants.
  • When a new canonical helper replaces older local variants, migrate or remove the overlapping variants instead of leaving parallel helper families behind.
  • Be careful with repeat-offender boundaries: prefer canonical helpers over fresh inline mocks for UI boundaries such as expo-router, @/text, @/modal, react-native, and react-native-unistyles; prefer existing server route/DB harnesses over direct storage mocks when available.
  • For apps/ui tests, treat apps/ui/sources/dev/testkit/** as the default surface. Read apps/ui/sources/dev/testkit/README.md first and prefer imports from @/dev/testkit for mocks, fixtures, render helpers, hook helpers, and harnesses.
  • Do not add new inline vi.mock(...) families for expo-router, @/text, @/modal, react-native, react-native-unistyles, or @/sync/domains/state/storage when the UI testkit already owns that boundary. If a needed case is missing, extend the canonical UI testkit helper in the same change instead of inventing a file-local mock family.
  • If a one-off local UI override is truly unavoidable, keep it minimal, base it on the canonical factory where possible, and leave a short justification comment rather than turning it into a new reusable pattern.
  • Prefer typed fixtures/builders from the owning testkit over repeated inline object literals whenever the same state/session/theme/config shape is reused across tests.
  • Keep package-specific fixtures near the owning package:
    • UI helpers in apps/ui
    • CLI helpers in apps/cli
    • server helpers in apps/server

UI E2E Rules

  • Use stable testID selectors, not visible copy, as the primary selector contract.
  • Click the real submit/confirm button after waiting for it to be enabled.
  • Do not rely on Enter-to-send or similar settings-sensitive shortcuts unless the test explicitly configures the setting first.
  • When a UI flow changes, update the corresponding Playwright spec in the same change.

Anti-Flake Process Rules

  • Keep only one active rerun per spec/lane.
  • If a runner hangs or is killed, inspect whether the failure is repo-owned, harness-owned, or environmental before retrying blindly.
  • When shared process helpers change, rerun a broader lane that can reveal leaked handles or child-process cleanup regressions.

Output Expectations

When reporting testing work, summarize:

  • failing area and classification
  • root cause
  • targeted RED/GREEN evidence
  • broader lane rerun performed
  • residual risk, if any