Testing Patterns

Comprehensive patterns for building production test suites. Each category has individual rule files in rules/ loaded on-demand.

Quick Reference

Category	Rules	Impact	When to Use
Unit Testing	3	CRITICAL	AAA pattern, parametrized tests, fixture scoping
Integration Testing	3	HIGH	API endpoints, database tests, component integration
E2E Testing	3	HIGH	Playwright, AI agents, page objects
Pytest Advanced	3	HIGH	Custom markers, xdist parallel, plugins
API Mocking	3	HIGH	MSW 2.x, VCR.py, LLM API mocking
Test Data	3	MEDIUM	Factories, fixtures, seeding/cleanup
Verification	3	MEDIUM	Property-based, stateful, contract testing
Performance	3	MEDIUM	k6 load tests, Locust, test types
LLM Testing	3	HIGH	Mock responses, DeepEval, structured output
Accessibility	3	MEDIUM	jest-axe, Playwright axe, CI gates
Execution	2	HIGH	Parallel runs (xdist/matrix), coverage thresholds/reporting
Validation	2	HIGH	Zod schema testing, tRPC/Prisma end-to-end type safety
Evidence	1	MEDIUM	Task completion verification, exit codes, evidence protocol

Total: 35 rules across 13 categories

Quick Start

# pytest: AAA pattern with fixtures
@pytest.fixture
def user(db_session):
    return UserFactory.create(role="admin")

def test_user_can_publish(user, article):
    result = article.publish(by=user)
    assert result.status == "published"

// Vitest + MSW: API integration test
const server = setupServer(
  http.get('/api/users', () => HttpResponse.json([{ id: 1 }]))
);
test('renders user list', async () => {
  render(<UserList />);
  expect(await screen.findByText('User 1')).toBeInTheDocument();
});

Unit Testing

Isolated business logic tests with fast, deterministic execution.

Rule	File	Key Pattern
AAA Pattern	rules/unit-aaa-pattern.md	Arrange-Act-Assert with Vitest/pytest
Parametrized Tests	rules/unit-parametrized.md	test.each, @pytest.mark.parametrize, indirect
Fixture Scoping	rules/unit-fixture-scoping.md	function/module/session scope selection

Integration Testing

Component interactions, API endpoints, and database integration.

Rule	File	Key Pattern
API Testing	rules/integration-api.md	Supertest, httpx AsyncClient, FastAPI TestClient
Database Testing	rules/integration-database.md	In-memory SQLite, transaction rollback, test containers
Component Integration	rules/integration-component.md	React Testing Library, QueryClientProvider

E2E Testing

End-to-end validation with Playwright 1.58+.

Rule	File	Key Pattern
Playwright Core	rules/e2e-playwright.md	Semantic locators, auto-wait, flaky detection
AI Agents	rules/e2e-ai-agents.md	Planner/Generator/Healer, init-agents
Page Objects	rules/e2e-page-objects.md	Page object model, visual regression

Pytest Advanced

Advanced pytest infrastructure for scalable test suites.

Rule	File	Key Pattern
Markers + Parallel	rules/pytest-execution.md	Custom markers, pyproject.toml, xdist loadscope, worker DB isolation
Plugins & Hooks	rules/pytest-plugins.md	conftest plugins, factory fixtures, async mode

API Mocking

Network-level mocking for deterministic tests.

Rule	File	Key Pattern
MSW 2.x	rules/mocking-msw.md	http/graphql/ws handlers, server.use() override
VCR.py	rules/mocking-vcr.md	Record/replay cassettes, sensitive data filtering
LLM API Mocking	rules/llm-mocking.md	Custom matchers, async VCR, CI record modes

Test Data

Fixture and factory patterns for test data management.

Rule	File	Key Pattern
Factory Patterns	rules/data-factories.md	FactoryBoy, faker, TypeScript factories
JSON Fixtures	rules/data-fixtures.md	Fixture composition, conftest loading
Seeding & Cleanup	rules/data-seeding-cleanup.md	Database seeding, autouse cleanup, isolation

Verification

Advanced verification patterns beyond example-based testing.

Rule	File	Key Pattern
Property-Based	rules/verification-techniques.md	Hypothesis strategies, roundtrip/idempotence
Stateful Testing	rules/verification-stateful.md	RuleBasedStateMachine, Schemathesis
Contract Testing	rules/verification-contract.md	Pact consumer/provider, broker CI/CD

Performance

Load and stress testing for capacity validation.

Rule	File	Key Pattern
k6 Patterns	rules/perf-k6.md	Stages, thresholds, custom metrics
Locust	rules/perf-locust.md	HttpUser tasks, on_start auth
Test Types	rules/perf-types.md	Load/stress/spike/soak profiles

LLM Testing

Testing patterns for AI/LLM applications.

Rule	File	Key Pattern
Mock Responses	rules/llm-mocking.md	AsyncMock, patch model_factory
LLM Evaluation	rules/llm-evaluation.md	DeepEval metrics, schema validation, timeout testing

Accessibility

Automated accessibility testing for WCAG compliance.

Rule	File	Key Pattern
A11y Testing	rules/a11y-testing.md	jest-axe, CI gates, PR blocking, component-level validation
Playwright axe	rules/a11y-playwright.md	Page-level wcag2aa scanning

Execution

Test execution strategies for parallel runs and coverage collection.

Rule	File	Key Pattern
Execution	rules/execution.md	Parallel execution, coverage reporting, CI optimization

Validation

Schema validation testing with Zod, tRPC, and end-to-end type safety.

Rule	File	Key Pattern
Zod Schema	rules/validation-zod-schema.md	safeParse testing, branded types, assertNever
End-to-End Types	rules/validation-end-to-end.md	tRPC, Prisma, Pydantic, schema rejection tests

Evidence

Evidence collection for verifiable task completion.

Rule	File	Key Pattern
Evidence Verification	rules/verification-evidence.md	Exit codes, test/build/quality evidence, protocol

Key Decisions

Decision	Recommendation
Unit framework	Vitest (TS), pytest (Python)
E2E framework	Playwright 1.58+ with semantic locators
API mocking	MSW 2.x (frontend), VCR.py (backend)
Test data	Factories over fixtures
Coverage targets	90% business logic, 70% integration, 100% critical paths
Performance tool	k6 (JS), Locust (Python)
A11y testing	jest-axe + Playwright axe-core
Runtime validation	Zod (safeParse at boundaries)
E2E type safety	tRPC (no codegen)
Branded types	Zod .brand() for ID confusion prevention
Evidence minimum	Exit code 0 + timestamp
Coverage standard	70% production, 80% gold

Detailed Documentation

Resource	Description
scripts/	Templates: conftest, page objects, MSW handlers, k6 scripts
checklists/	Pre-flight checklists for each testing category
references/	API references: Playwright, MSW 2.x, DeepEval, strategies
examples/	Complete test examples and patterns

Related Skills

• test-standards-enforcer - AAA and naming enforcement
• run-tests - Test execution orchestration
• golden-dataset-validation - Golden dataset testing
• observability-monitoring - Metrics and monitoring