# ADR-0028: Testing Strategy

## Status
Accepted

## Context
The platform needs a comprehensive testing strategy:
- Unit tests for individual components
- Integration tests for full flows
- Contract tests for API compatibility
- Load tests for performance

Testing tools and approaches vary in complexity and coverage.

## Decision
Adopt a **multi-layered testing approach**:

1. **Unit tests**:
   - Tool: Standard `testing` package + `testify`
   - Coverage: >80% for core modules
   - Mocks: `mockery` or `mockgen`
   - Fast execution (< 1 second)

2. **Integration tests**:
   - Tool: `testcontainers-go` for Docker-based services
   - Coverage: End-to-end flows (auth, modules, etc.)
   - Infrastructure: PostgreSQL, Redis, Kafka via testcontainers
   - Tagged: `//go:build integration`

3. **Contract tests**:
   - Tool: OpenAPI validator (`kin-openapi`)
   - Coverage: API request/response validation
   - Optional: Pact for service contracts

4. **Load tests**:
   - Tool: k6 or vegeta
   - Coverage: Critical endpoints (auth, API)
   - Performance benchmarks

**Rationale:**
- Comprehensive coverage across layers
- Fast feedback with unit tests
- Realistic testing with integration tests
- API compatibility with contract tests
- Performance validation with load tests

## Consequences

### Positive
- High confidence in code quality
- Fast unit tests for quick feedback
- Realistic integration tests
- API compatibility guaranteed

### Negative
- Integration tests are slower
- Requires Docker for testcontainers
- More complex CI setup

### Implementation Notes
- Use `testify` for assertions: `require` and `assert`
- Generate mocks with `mockery` or `mockgen`
- Create test helpers in `internal/testutil/`
- Use test tags: `go test -tags=integration ./...`
- Run integration tests in separate CI job
- Document testing approach in `CONTRIBUTING.md`