Shift-Left Testing

<defaulttoaction> When implementing early testing practices:

1. VALIDATE requirements before coding (testability, BDD scenarios)
2. WRITE tests before implementation (TDD)
3. AUTOMATE in CI pipeline (every commit triggers tests)
4. FIX defects immediately - never let them accumulate

Quick Shift-Left Levels:

• Level 1: Unit tests with each PR (developer responsibility)
• Level 2: TDD practice (tests before code)
• Level 3: BDD/Example mapping in refinement (requirements testing)
• Level 4: Risk analysis in design (architecture testing)

</defaulttoaction>

Quick Reference Card

When to Use

• Reducing cost of defects
• Implementing CI/CD pipelines
• Starting TDD practice
• Improving requirements quality

Shift-Left Levels

Level 1: Tests in Every PR

# CI pipeline - tests run on every commit
name: CI
on: [push, pull_request]
jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: npm ci
      - run: npm run test:unit
      - run: npm run test:integration
      - run: npm run lint

  quality-gate:
    needs: test
    steps:
      - name: Coverage Check
        run: npx coverage-check --min 80
      - name: No New Warnings
        run: npm run lint -- --max-warnings 0

Agent-Assisted Shift-Left

// Validate requirements testability
await Task("Requirements Validation", {
  requirements: userStories,
  check: ['INVEST-criteria', 'testability', 'ambiguity'],
  generateBDD: true
}, "qe-requirements-validator");

// Generate tests from requirements
await Task("Generate Tests", {
  source: 'requirements',
  types: ['unit', 'integration', 'e2e'],
  coverage: 'comprehensive'
}, "qe-test-generator");

// Smart test selection for changes
await Task("Select Regression Tests", {
  changedFiles: prFiles,
  algorithm: 'risk-based',
  targetReduction: 0.7  // 70% time savings
}, "qe-regression-risk-analyzer");

Agent Coordination Hints

Memory Namespace

aqe/shift-left/
├── requirements/*       - Validated requirements
├── generated-tests/*    - Auto-generated tests
├── coverage-targets/*   - Coverage goals by component
└── pipeline-results/*   - CI/CD test history

Fleet Coordination

const shiftLeftFleet = await FleetManager.coordinate({
  strategy: 'shift-left',
  agents: [
    'qe-requirements-validator',     // Level 3-4
    'qe-test-generator',             // Level 2
    'qe-regression-risk-analyzer'    // Smart selection
  ],
  topology: 'sequential'
});

Related Skills

• [tdd-london-chicago](../tdd-london-chicago/) - TDD practices
• [holistic-testing-pact](../holistic-testing-pact/) - Proactive testing
• [cicd-pipeline-qe-orchestrator](../cicd-pipeline-qe-orchestrator/) - Pipeline integration
• [shift-right-testing](../shift-right-testing/) - Production feedback

Remember

With Agents: Agents validate requirements testability, generate tests from specs, and select optimal regression suites. Use agents to implement shift-left practices consistently.

Skill Composition

• TDD practice → Use /tdd-london-chicago for specific TDD guidance
• Generate tests → Use /qe-test-generation for AI-powered test generation
• CI/CD quality → Use /cicd-pipeline-qe-orchestrator for pipeline setup

Gotchas

• "Shift left" doesn't mean "only test left" — production monitoring (shift right) is still needed
• Agent generates tests before understanding requirements — tests for wrong behavior are worse than no tests
• CI pipeline tests that take >10 minutes kill the feedback loop — keep commit-stage tests under 5 minutes
• TDD discipline degrades when agent writes test+code simultaneously — enforce Red phase separation
• Shifting left without lightweight environments just shifts the bottleneck — fix environments first