Test Tier Selection

---
created: 2025-12-16
modified: 2026-07-31
reviewed: 2026-04-25
name: test-tier-selection
description: "Auto-select test tiers based on change scope — unit for small, full suite for large. Use when running tests, discussing testing strategy, or after code modifications."
user-invocable: false
allowed-tools: Read, Glob, Grep
---

# Test Tier Selection

Automatic guidance for selecting appropriate test tiers based on change context and scope.

## When to Use This Skill

| Use this skill when... | Use test-consult instead when... |
|---|---|
| Mechanically deciding which tier to run for a given change | Reviewing overall test pyramid balance or strategy |
| Mapping change type (refactor, API, UI) to required tiers | Designing a new feature's test approach |
| Justifying why an E2E run is or isn't needed | Diagnosing flaky tests in an existing suite |
| Picking between test-quick, test-run, and test-full | Setting up a project's test infrastructure (use test-setup) |

## Test Tier Definitions

| Tier | Duration | Scope | When to Run |
|------|----------|-------|-------------|
| **Unit** | < 30s | Single function/module | After every code change |
| **Integration** | < 5min | Component interactions | After feature completion |
| **E2E** | < 30min | Full user flows | Before commit/PR |

## Decision Matrix

### Change Type → Test Tier

| Change Type | Unit | Integration | E2E |
|-------------|------|-------------|-----|
| Single function fix | Required | Skip | Skip |
| New feature (1 file) | Required | Required | Skip |
| Multi-file feature | Required | Required | Required |
| Refactoring | Required | Required | Optional |
| API changes | Required | Required | Required |
| UI changes | Required | Optional | Required |
| Bug fix (isolated) | Required | Optional | Skip |
| Database changes | Required | Required | Required |
| Config changes | Required | Required | Optional |

## Escalation Signals

**Escalate to Integration when:**
- Changes span multiple files
- Business logic affected
- Service boundaries modified
- Database queries changed

**Escalate to E2E when:**
- User-facing features modified
- Authentication/authorization changes
- Critical path functionality
- Before creating PR

## Commands by Tier

```bash
# Tier 1: Unit (fast feedback)
/test:quick

# Tier 2: Integration (feature completion)
/test:full --coverage

# Tier 3: E2E (pre-commit)
/test:full
```

## Agent Consultation Triggers

**Consult `test-architecture` agent when:**
- New feature module created
- Coverage drops > 5%
- > 3 flaky tests detected
- Framework questions arise
- Test strategy needs adjustment

**Consult `test-runner` agent when:**
- Need test execution with analysis
- Multiple failures to diagnose
- Want concise failure summary

**Consult `system-debugging` agent when:**
- Integration test failures with unclear cause
- Environment/timing issues
- Flaky tests related to concurrency

## Quick Reference

### After Small Change
```
1. Run /test:quick
2. If pass: Continue working
3. If fail: Fix immediately
```

### After Feature Completion
```
1. Run /test:full --coverage
2. Check coverage targets met
3. If gaps: /test:consult coverage
```

### Before Commit/PR
```
1. Run /test:full
2. All tiers must pass
3. Review coverage report
```

### For New Features
```
1. /test:consult new-feature
2. Write tests (TDD)
3. Run /test:quick during development
4. Run /test:full before PR
```

## Activation Triggers

This skill auto-activates when:
- User mentions "test", "run tests", "testing"
- After code modification by Claude
- During TDD workflow
- When `/test:*` commands invoked
- When discussing test strategy