Testing selection

Testing Selection

Purpose

Decide the test types and tools for the project from its actual applications and risks — the right pyramid per app, and the specific tools that fit — so effort lands where failure hurts. Refines the core ../../testing-strategy for concrete tooling; requires the application/stack decisions as input.

When to Use

• After applications and stack are chosen (../../application-selection, ../../stack-recommendation), when planning how the project is tested.
• When adding an application that changes the testing surface.
• Not for writing tests (the per-type skills) or per-bug regression (regression-testing).

Inputs

• Selected applications (web, dashboard, mobile, backend API) and their risk/criticality.
• Stack per area (drives tool fit) and existing test setup if any (../../existing-project-audit).

Discovery Questions

• Which applications exist, and what does each break if untested (money, auth, data loss)?
• What is the runtime per app (Node/TS backend, React web, React Native mobile) — which tools are idiomatic?
• Which flows are critical enough to warrant E2E, and which are covered cheaper at lower levels?
• Is there existing test tooling to extend rather than replace?

Responsibilities

• Map each application to its levels + tools, adopting only what's needed:
  • Unit + integration logic → Jest or Vitest (one, per stack convention — Vitest for Vite/modern TS, Jest where established); pure logic, services, reducers, hooks.
  • Backend API integration → Supertest (real HTTP against the app + real DB) — pairs with ../../backend/backend-integration-testing.
  • Component/interaction → Testing Library (React / React Native) — accessible queries, user-facing behavior.
  • Web/dashboard E2E → Playwright — critical browser flows only.
  • Mobile E2E + smoke → Maestro — critical device flows only.
  • Contract → contract-testing where independently deployed clients/services must agree.
• Set the pyramid shape per app: many unit, fewer integration, few E2E — E2E is expensive and slow, reserved for critical end-to-end journeys.
• Record what is not adopted and why (no Playwright if there's no web app; no Maestro without mobile) — absence is a decision.
• Feed the choices to ../../devops/ci-cd (jobs are generated from selected apps + selected test types) and to the per-type skills.

Required Workflow

1. List applications with risk/criticality.
2. Assign levels + tools per app (adopt minimally).
3. Fix the pyramid shape and which flows earn E2E.
4. Record non-adoptions with reasons.
5. Hand off to the per-type skills and ../../devops/ci-cd.

Decision Rules

• One unit/integration runner per stack — not Jest and Vitest in the same app without cause.
• E2E tool follows the platform: Playwright for browsers, Maestro for devices — not one tool stretched across both.
• Supertest is the backend API-integration default (Node); it doesn't replace unit tests or E2E.
• Adopt a tool only when an application needs it; "might need it later" is not now.
• Risk drives depth, not a coverage number (test-coverage-audit).

Rules

• Selection is recorded and tied to specific applications.
• No tool adopted for an application that doesn't exist.
• The selection drives CI job generation — keep them in sync.

Anti-Patterns

• Adopting the full toolchain on every project reflexively.
• Playwright with no web app; Maestro with no mobile app.
• E2E-heavy pyramids (slow, flaky, expensive) instead of unit-heavy.
• Two unit runners in one app.
• Choosing tools before knowing the applications.

Validation Checklist

• Applications listed with risk.
• Levels + tools assigned per app, minimally.
• Pyramid shape + E2E-worthy flows fixed.
• Non-adoptions recorded with reasons.
• Handed to per-type skills + ../../devops/ci-cd.

Definition of Done

A recorded per-application test-type-and-tool selection — Jest/Vitest, Supertest, Testing Library, Playwright, Maestro adopted only where an application justifies them — with the pyramid shape set and non-adoptions explained, feeding CI generation.

Related Skills

../../testing-strategy, unit-testing, integration-testing, api-integration-testing, contract-testing, playwright-e2e, maestro-e2e, ../../devops/ci-cd, ../../application-selection, ../../stack-recommendation.

Related Knowledge

../../../knowledge/ (application risk, critical flows).

Related References

../../../references/testing/ (tool-fit notes, when populated).

Context Loading Guidance

• Requires: selected applications with risk, stack per area.
• Does not require: test code, the full skill set, unrelated references.
• May load: the per-type skills after selecting, ../../devops/ci-cd.
• Stop when: the per-application selection is recorded.

Token Efficiency Guidance

The application × (levels, tools) table is the artifact; decide per app, don't survey every tool for every app.