Testing & Deployment

Unit and Integration Testing

Jest and Vitest run unit tests with mocking built in. Test pure functions without I/O and mock database modules at repository boundaries.

Supertest hits Express apps in-memory without binding ports. Spin up Testcontainers for integration tests against real PostgreSQL or Redis.

Separate fast unit suites from slower integration jobs in CI for quick feedback.

• Reset database state between integration tests
• Use NODE_ENV=test with separate config
• Measure coverage but prioritize critical paths over 100%

import request from 'supertest';
import { app } from '../app.js';

test('GET /health', async () => {
  const res = await request(app).get('/health');
  expect(res.status).toBe(200);
});

Docker and CI

Multi-stage Dockerfiles install dependencies, build TypeScript, and copy minimal runtime artifacts into slim production images. Run as non-root users.

CI pipelines lint, test, build images, and deploy on green main. Cache npm dependencies for speed.

Health checks and graceful shutdown hooks integrate with orchestrators like Kubernetes.

• Use .dockerignore to exclude node_modules and tests
• Pass secrets via orchestrator secrets, not ENV in Dockerfile
• Tag images with git SHA for traceability

FROM node:20-alpine AS build
WORKDIR /app
COPY package*.json ./
RUN npm ci
COPY . .
RUN npm run build

FROM node:20-alpine
WORKDIR /app
COPY --from=build /app/dist ./dist
CMD ["node", "dist/index.js"]

Production Deployment

Deploy to AWS ECS, Fly.io, Railway, Render, or traditional VMs with systemd. Use reverse proxies (nginx, Caddy) for TLS termination when not handled by platform.

Configure NODE_ENV=production, logging aggregation, and alerts on error rates and latency SLOs.

Run database migrations as separate release steps before switching traffic to new app versions.

• Implement /health and /ready endpoints for load balancers
• Use structured JSON logging for searchability
• Practice rollback procedures before launch day