testing-strategy

name	testing-strategy
description	Testing strategy, patterns, and quality assurance for the project. Covers vitest patterns, external integration test design (mocking transport, simulating reconnect, checksum validation for streaming sources), domain math test design (boundary values, precision edge cases), E2E multi-process testing (IPC, worker lifecycle), route testing (auth verification, input validation), database test patterns (mocking data layer), chaos test framework design, test quality metrics (mutation testing, branch coverage), React component/hook testing (RTL query priority, MSW network mocking, axe a11y), test-first TDD (RED/GREEN/REFACTOR discipline), and CI integration. Use when writing tests, reviewing test quality, designing test strategies, setting up CI pipelines, or evaluating test coverage gaps.
owner	QA Architect (archetype)
version	1.1.0
inspired_by	[{"source":"affaan-m/ecc/skills/react-testing@81af40761939056ab3dc54732fd4f562a27309d0","license":"MIT","relationship":"structural_inspiration","authored_by":"ceo-orchestration framework","authored_at":"2026-07-07T00:00:00.000Z"},{"source":"affaan-m/ecc/skills/tdd-workflow@81af40761939056ab3dc54732fd4f562a27309d0","license":"MIT","relationship":"structural_inspiration","authored_by":"ceo-orchestration framework","authored_at":"2026-07-07T00:00:00.000Z"}]
source	affaan-m/ecc@81af4076 skills/react-testing/ + skills/tdd-workflow/
license	MIT
domain	core
priority	4
risk_class	low
stack	["pytest","jest"]
context_budget_tokens	1100
inactive_but_retained	false
repo_profile_binding	{"frontend":{"active":true,"priority":4},"engine":{"active":true,"priority":4},"fintech":{"active":true,"priority":4},"trading-readonly":{"active":true,"priority":5},"generic":{"active":true,"priority":4}}
activation_triggers	[{"event":"file-edit","glob":"**/test_*.py"},{"event":"file-edit","glob":"**/*.test.{ts,tsx,js,jsx}"}]

Testing Strategy

Examples use vitest, but the patterns apply to Jest, Mocha, pytest, Go testing, and any mainstream test runner.

When to Activate

Read this skill when you are:

• writing or reviewing tests (unit, integration, E2E multi-process, chaos) in any mainstream runner;
• designing a test strategy for a new module or auditing coverage gaps;
• setting up or hardening a CI pipeline that gates deploy on tests;
• evaluating test QUALITY (mutation score, planted-bug reviewer evals), not just test quantity;
• writing behavior-focused tests for React components, custom hooks, or pages (see references/react-component-testing.md);
• running a test-first RED/GREEN/REFACTOR cycle for a new feature or bug fix (see references/tdd-red-green-cycle.md);
• editing files matched by the machine triggers in the frontmatter (**/test_*.py, **/*.test.{ts,tsx,js,jsx}).

The machine-first activation_triggers frontmatter remains the canonical auto-load rule; this section is its human-scannable mirror.

Current State

Metric	Value	Assessment
Total tests	(measure)	Track passing/failing
Test files	(measure)	In src/__tests__/ or equivalent
TypeScript errors	0 target	tsc --noEmit clean
Framework	vitest 4.x	Fast, ESM-native
E2E multi-process tests	(measure)	Often a gap
Stress/chaos tests	(measure)	Often a gap
CI test execution	required	Tests must run before deploy
Mutation testing	(optional)	Verifies test quality
Branch coverage	(measure)	Should be tracked

Key Principle

A passing test suite is not a quality signal unless the tests themselves are audited. Happy-path tests without error-path, auth, multi-process, and edge-case coverage can give a false sense of safety.

Reference Files — progressive disclosure (PLAN-153 Wave C)

The deep-dive sections of this skill were extracted VERBATIM into the ten Wave-C references/*.md files listed below — zero content loss (every content line of the pre-split SKILL.md appears verbatim either in this file or in one of those ten references; the loader additionally ADDS loader-only sections — When to Activate, the pointer tables, the changelog). Load on demand:

Load references/<file>	For
vitest-patterns.md	Runner config, test-file conventions, standard structure, core rules
integration-testing.md	External-integration tests: mock transport, checksum validation, reconnect simulation
domain-math-and-property-based.md	Boundary values, decimal-precision edge cases, property-based tests
e2e-multiprocess.md	E2E multi-process/IPC test design, worker lifecycle
route-testing.md	Route auth-verification and input-validation tests
database-testing.md	Mock data layer, RLS/access-control test patterns
chaos-testing.md	Chaos framework: IPC failure, memory pressure, upstream disconnect, DB outage
test-quality-and-mutation.md	Mutation testing, branch coverage, planted-bug behavioral evals, quality checklist
ci-integration.md	Required CI pipeline shape + CI rules
module-test-matrices.md	Per-module what-to-test priority tables

Merged-in references (PLAN-153 Wave G — clean-room ADAPT)

These two references carry knowledge ported clean-room and adapted into our voice (provenance in the inspired_by: frontmatter). They are NOT verbatim extractions, so they do not participate in the Wave-C verbatim-union invariant above — treat them as first-party framework content authored during the Wave-G merge. Load on demand:

Load references/<file>	For
react-component-testing.md	React component & hook tests: RTL query priority, userEvent, MSW network mocking, axe a11y assertions, snapshot boundaries, and the RTL-vs-Playwright decision line
tdd-red-green-cycle.md	Test-first RED/GREEN/REFACTOR discipline: the RED-gate proof obligation, test-runner detection, git checkpoints, and the TDD evidence report

Anti-Patterns to Reject

Anti-Pattern	Why It's Wrong	Correct Approach
Test only happy path	Misses error handling bugs	Test error paths and edge cases
Mock everything	Tests pass but system broken	Integration tests for critical paths
Test implementation, not behavior	Breaks on refactor	Test inputs and outputs
Shared mutable state between tests	Flaky, order-dependent	Fresh setup per test
expect(true).toBe(true)	Vacuous truth	Assert specific values from computation
Skipping flaky tests	Hidden failures	Fix the flake or delete the test
No tests for auth	Privileged routes ship unauthed	Every route MUST have auth test
Testing in production only	Typo deploys to prod	CI runs tests before deploy
any in test types	Hides type mismatches	Use proper types in tests too
Testing private methods	Couples to implementation	Test via public interface

Adopter Note — Runner Framing + Example Biases (PLAN-044 P0-12)

This skill's top portability note ("Examples use vitest, but the patterns apply to Jest, Mocha, pytest, Go testing, and any mainstream test runner") is honest — but several subsections below carry originating-project biases that are worth naming explicitly for fresh adopters:

• §Current State table lists Framework: vitest 4.x, src/__tests__/ location, and TypeScript errors: 0 target / tsc --noEmit clean. Replace with your runner, your test-file location, and your typecheck tool before citing in review.

• §External integration test design references mocking transport, simulating reconnect, checksum validation for streaming sources — that is the originating ingestion- engine's test shape. Your integration-test shape may be HTTP-mocking, fixture-replay, or sandbox-environment.

• §Domain math tests reference boundary values, precision edge cases — universal when your domain has math, but the originating-project examples come from financial- instrument pricing. Substitute your own domain's boundary cases.

• §E2E multi-process tests (IPC, worker lifecycle) assume Node's cluster/worker model. On other runtimes the equivalent is different (Python multiprocessing, Go goroutine test harnesses, JVM test containers).

• references/react-component-testing.md and references/tdd-red-green-cycle.md are JS/TS-flavored (RTL, MSW, bun test vs bun run test). The principles — accessible queries, network-seam mocking, the RED-gate proof obligation, and the evidence report — transfer to any stack; the tool names do not.

The patterns (mocking at the transport seam, asserting on observable state not private calls, mutation testing to verify test quality, CI-runs-tests-before-deploy) all transfer. The tool names and file paths do not.

Changelog

• 1.1.0 (2026-07-09, PLAN-153 Wave G, SP-026): two clean-room ADAPT merges added as NEW references — react-component-testing.md (React Testing Library / MSW / axe) and tdd-red-green-cycle.md (test-first RED/GREEN/REFACTOR + evidence report), both ported clean-room (provenance in inspired_by: frontmatter). Core gains two pointer rows, an activation-cue pair, and an adopter-note bullet; no Wave-C content changed. Soak: parallel-shadow (OQ3=c) until >= 2026-07-14. Adds zero to the skill count (references, not new SKILL.md files).
• 1.0.0 (2026-07-07, PLAN-153 Wave C, SP-022): progressive-disclosure restructure — deep-dive sections extracted verbatim to references/*.md; added version: frontmatter, this changelog, and the human-scannable ## When to Activate section. Zero change to the extracted content. Skill-Import-Attestation: reviewed-by=AE9B236FDAF0462874060C6BCFCFACF00335DC74; sha256=5dfa88aa074f04d89de90890e26195c737a935d51fb26f99a49c455820fbca3a