Master automated testing in CI/CD pipelines. Build applications, run test suites, generate coverage reports, and use matrix strategies for cross-platform testing.

Learning Objectives

Build applications automatically in CI pipelines

Run automated test suites on every commit

Generate and upload test coverage reports

Use matrix builds for multi-version testing

Upload and download build artifacts

Step 1

Create a project with tests

Set up a Node.js application with a proper test suite.

Commands to Run

mkdir cicd-testing && cd cicd-testing

npm init -y

npm install --save express

npm install --save-dev jest supertest

cat > app.js << 'EOF'
const express = require('express');
const app = express();

app.get('/', (req, res) => {
  res.json({ message: 'Hello CI/CD!' });
});

app.get('/health', (req, res) => {
  res.json({ status: 'healthy' });
});

module.exports = app;
EOF

cat > server.js << 'EOF'
const app = require('./app');
const port = process.env.PORT || 3000;

app.listen(port, () => {
  console.log(`Server running on port ${port}`);
});
EOF

cat > app.test.js << 'EOF'
const request = require('supertest');
const app = require('./app');

describe('API Endpoints', () => {
  test('GET / returns message', async () => {
    const response = await request(app).get('/');
    expect(response.status).toBe(200);
    expect(response.body.message).toBe('Hello CI/CD!');
  });

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

npx json -I -f package.json -e 'this.scripts.test="jest"'

npx json -I -f package.json -e 'this.scripts.start="node server.js"'

npm test

What This Does

We create a REST API with two endpoints and comprehensive tests. The app.js exports the Express app separately from server.js, making it testable with supertest.

Expected Outcome

Tests pass successfully. You'll see '2 passed' in the test output. This proves our application works before we automate it in CI.

Pro Tips

1
Separating app from server allows testing without starting the server
2
supertest makes HTTP endpoint testing simple
3
All tests should pass locally before pushing to CI
4
Use descriptive test names that explain what's being tested

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