shift-left-testing

name	shift-left-testing
description	Move testing activities earlier in the development lifecycle to catch defects when they're cheapest to fix. Use when implementing TDD, CI/CD, or early quality practices.
category	testing-methodologies
priority	high
tokenEstimate	900
agents	["qe-test-generator","qe-requirements-validator","qe-regression-risk-analyzer"]
implementation_status	optimized
optimization_version	1
last_optimized	"2025-12-02T00:00:00.000Z"
dependencies	[]
quick_reference_card	true
tags	["shift-left","early-testing","tdd","bdd","ci-cd","prevention"]
trust_tier	3
validation	{"schema_path":"schemas/output.json","validator_path":"scripts/validate-config.json","eval_path":"evals/shift-left-testing.yaml"}

Shift-Left Testing

<default_to_action> 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) </default_to_action>

Quick Reference Card

When to Use

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

Shift-Left Levels

Level	Practice	When
1	Unit tests in PR	Before merge
2	TDD	Before implementation
3	BDD/Example Mapping	During refinement
4	Risk Analysis	During design

---

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