Integration Test & E2E Test Design/Implementation Rules

References

references/e2e-design.md - E2E test design principles with Playwright (candidate properties, selection criteria, candidate record)
references/e2e-environment-prerequisites.md - service-integration-e2e environment prerequisites (seed data, auth fixtures, environment checklist); fixture-e2e requires no live service or real database

Test Type	Purpose	Scope	External Deps	File Format	Implementation Timing
Integration	Verify component interactions in-process	Partial system integration (in-process modules; for UI components, RTL+MSW for React/TS)	Mocked or in-process	`*.int.test.ts`	Created alongside implementation
fixture-e2e	Verify browser behavior with deterministic fixtures	Full UI flow with mocked backend / fixture-driven state	Mocked / fixture only — no live services	`*.fixture-e2e.test.ts`	Created alongside the UI feature
service-integration-e2e	Verify a contract that only a running stack can expose	Full system across services	Live local services or service-level stubs	`*.service-e2e.test.ts`	Executed after the required services exist

Lane selection (E2E only):

Default lane for user-facing UI journeys is fixture-e2e — it runs a real browser against deterministic fixtures, catches the bugs that unit/integration tests miss (button no-op, state never updates, navigation breaks), and runs in CI without infrastructure setup
Select service-integration-e2e when the proof obligation is real cross-service behavior such as data persistence, transactional consistency, or an external service contract