Best Practices for Test-Driven Development (TDD)
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As part of the “Best Practices” series by Uplatz
Welcome to this discipline-first edition of the Uplatz Best Practices series — where quality is built in, not tested in.
Today’s focus: Test-Driven Development (TDD) — a software development process that leads to better code, faster debugging, and more confident releases.
🧪 What is Test-Driven Development?
Test-Driven Development (TDD) is a development methodology where tests are written before the code that satisfies them.
It follows a simple 3-step cycle:
- Red – Write a failing test for a new feature
- Green – Write just enough code to make the test pass
- Refactor – Clean up the code while keeping the test green
This loop ensures that every line of code is justified by a test.
✅ Best Practices for Test-Driven Development (TDD)
TDD is about thinking before coding — and validating intent with precision. Here’s how to do it right:
1. Write the Smallest Failing Test First
🧪 Keep Your Initial Test Narrow and Focused
❌ Avoid Testing Multiple Behaviors at Once
📏 Use Assert-First Thinking: What Do You Expect the Code to Do?
2. Focus on Behavior, Not Implementation
🎯 Write Tests Based on External Outputs or Effects
📦 Don’t Hardwire Tests to Internal Variables or Functions
🧠 Let Tests Guide Design, Not Dictate Structure
3. Keep Tests Fast and Independent
⚡ Avoid External Dependencies (e.g., DB, network)
🔁 Mock or Stub I/O Where Necessary
🏃 Run Tests Frequently Without Waiting
4. Refactor Relentlessly
🧹 Refactor Code After the Test Passes — But Keep Tests Passing
📦 Consolidate Logic, Remove Duplication, Improve Naming
🧠 Refactor Tests Too — They’re First-Class Citizens
5. Use Descriptive Test Names
📘 Name Tests to Express Intent: should_throw_if_password_is_empty()
📎 Helps in Debugging, Code Reviews, and Test Reporting
✅ Follows Readability over Brevity
6. Organize Test Files Strategically
🗂️ Mirror Production Code Structure
📦 Group by Feature or Module (not by test type)
🔍 Easy Discoverability for Developers and CI Systems
7. Use Mocks and Fakes Judiciously
🧪 Mock External Dependencies (email, APIs, queues)
🚫 Don’t Overuse Mocks for Core Logic — That Breaks Refactoring
🧩 Use Test Doubles Only Where Needed
8. Integrate TDD With CI/CD
🔄 Run Tests on Every Commit and Pull Request
📈 Track Coverage and Performance Metrics Automatically
🧪 Fail Builds if Tests Fail — Treat as Production Bugs
9. Educate Teams on TDD Discipline
🎓 Run Internal TDD Dojos or Pairing Sessions
🤝 Pair Juniors With Seniors to Reinforce Patterns
🧱 Start With Greenfield Projects or Isolated Modules
10. Use TDD for Design Feedback
🔄 Let Tests Reveal Design Pain Points (e.g., hard-to-test code)
🧠 Use That Feedback to Restructure Code for Better Modularity
🧱 TDD Is as Much About Design as It Is About Testing
💡 Bonus Tip by Uplatz
TDD isn’t slow — broken code is.
Think tests-first, write better code later. Discipline now, velocity forever.
🔁 Follow Uplatz to get more best practices in upcoming posts:
- Behavior-Driven Development (BDD)
- Continuous Testing in Agile
- Writing Mocks With Test Containers
- Using TDD With Microservices
- Refactoring Legacy Code With TDD
…and more on software quality, test architecture, and agile engineering.