TDD & CI/CD

This article provides a glossary entry for TDD and CI/CD, including exam questions, core components, and key topics.

In a Nutshell

TDD: Tests are written before code (Red–Green–Refactor). CI/CD: automated integration and delivery via pipelines.

Technical Overview

TDD follows this cycle:

• Red: Write a test that fails
• Green: Write minimal code to pass the test
• Refactor: Improve code without changing functionality

CI/CD:

• CI: Build and test run automatically after every commit
• CD: Automated delivery (Delivery to staging, Deployment to production)

Exam Essentials

• TDD = test first
• Red-Green-Refactor cycle
• CI = automated build and testing
• CD = automated delivery (IHK-relevant)
• TDD increases test coverage
• CI/CD reduces manual errors (security benefit)
• Faster releases (business value)
• Pipeline must be documented

Core Components

1. Unit Tests
2. Test frameworks (JUnit/pytest)
3. CI servers (Jenkins/GitHub Actions)
4. Build tools
5. Containers/Deployment
6. Pipeline scripts
7. Rollback strategies
8. Staging environments
9. Code quality tools

Practical Example (pytest)

def add(a, b):
  return a + b

def test_add():
  assert add(2, 3) == 5

Advantages and Disadvantages

Advantages

• Higher code quality
• Automated QA
• Faster debugging
• Repeatable deployments

Disadvantages

• Initial setup effort
• Infrastructure required
• Discipline needed

Common Exam Questions (with Quick Answers)

1. What does Red-Green-Refactor mean? Write a test, implement minimally to pass it, then refactor.
2. Goal of CI? Automated testing and integration.
3. Delivery vs Deployment? Delivery reaches staging, Deployment reaches production.

Open-Ended Response

TDD forces you to think about requirements and interfaces early. In a DevOps context, CI/CD is now standard practice and demonstrates professionalism in real projects.

Learning Strategy

1. Build a small function using TDD.
2. Set up a GitHub Actions pipeline for build and test.
3. Sketch your pipeline on paper (useful for exams).
4. Never deploy without tests.

Key Resources

1. https://martinfowler.com/bliki/TestDrivenDevelopment.html
2. https://docs.github.com/en/actions