Smoke and Sanity Testing

Smoke tests verify the application hasn't fallen over. Not that it's correct.

Must cover:
  ✓ Service is responding (health endpoint returns 200)
  ✓ Database is connected (DB health check passes)
  ✓ Authentication flow works (can log in)
  ✓ Critical happy paths work (can browse products, can add to cart)
  ✓ Key third-party integrations responding (payment ping, email ping)

Should NOT cover:
  ✗ Edge cases
  ✗ Permissions for every role
  ✗ Full regression across all features

# tests/smoke/test_smoke.py
import pytest
import httpx

BASE_URL = os.environ.get("APP_URL", "https://staging.myapp.com")

@pytest.fixture(scope="session")
def client():
    with httpx.Client(base_url=BASE_URL, timeout=30) as c:
        yield c

def test_health_endpoint_ok(client):
    response = client.get("/health")
    assert response.status_code == 200
    assert response.json()["status"] == "healthy"

def test_database_healthy(client):
    response = client.get("/health/db")
    assert response.status_code == 200

def test_homepage_loads(client):
    response = client.get("/")
    assert response.status_code == 200
    assert len(response.text) > 100

def test_login_api_responds(client):
    response = client.post("/api/auth/token", json={
        "email": os.environ["SMOKE_USER_EMAIL"],
        "password": os.environ["SMOKE_USER_PASSWORD"],
    })
    assert response.status_code == 200
    assert "access_token" in response.json()

def test_products_api_returns_data(client):
    token = get_token(client)
    response = client.get("/api/products", headers={"Authorization": f"Bearer {token}"})
    assert response.status_code == 200
    assert len(response.json()["data"]) > 0

# .github/workflows/ci.yaml
jobs:
  smoke:
    needs: [deploy-staging]         # runs after staging deploy
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v4
    - run: pip install pytest httpx
    - name: Run smoke tests
      env:
        APP_URL: ${{ vars.STAGING_URL }}
        SMOKE_USER_EMAIL: ${{ secrets.SMOKE_USER_EMAIL }}
        SMOKE_USER_PASSWORD: ${{ secrets.SMOKE_USER_PASSWORD }}
      run: pytest tests/smoke/ -v --timeout=60 --tb=short

    integration:                    # smoke gates this
      needs: [smoke]
      ...

Bug fix: "Order total wasn't including VAT"
Sanity test: place an order and verify the total = subtotal + VAT (exact calculation)
             verify the invoice shows the VAT breakdown
             verify the VAT rate changes correctly for different product categories

Feature: "Added promo code support"
Sanity test: apply a valid promo code → correct discount applied
             apply an expired promo code → rejected with clear error
             apply a promo code with usage limit reached → rejected

Don't run the full regression during sanity — just the affected area.
If sanity fails, return the build. Don't proceed to regression.

# AWS Lambda — synthetic canary (runs every 5 min against production)
import urllib.request
import json

def handler(event, context):
    checks = [
        ("Health endpoint", "https://api.myapp.com/health"),
        ("Products API", "https://api.myapp.com/api/products"),
        ("Homepage", "https://www.myapp.com/"),
    ]

    failures = []
    for name, url in checks:
        try:
            with urllib.request.urlopen(url, timeout=10) as resp:
                if resp.status != 200:
                    failures.append(f"{name}: HTTP {resp.status}")
        except Exception as e:
            failures.append(f"{name}: {e}")

    if failures:
        raise Exception(f"Smoke failures: {', '.join(failures)}")

    return {"statusCode": 200, "body": f"All {len(checks)} checks passed"}