Software Engineering basics - What is Test-Driven Development (TDD) in Software Engineering?

Q: What is Test-Driven Development (TDD) in Software Engineering? Test-Driven Development (TDD) is a software development practice where developers write automated tests before writing the actual code. The goal is to ensure that every piece of functionality is verified against clear expectations from the start, which improves software quality and reduces bugs.

TDD typically follows the “Red–Green–Refactor” cycle:

1. Red: Write a test for a new feature or function. Since the feature doesn’t exist yet, the test fails.

2. Green: Write the minimum amount of code needed to make the test pass.

3. Refactor: Clean up the code while ensuring all tests still pass, improving readability and maintainability.

This process encourages developers to think about requirements and edge cases early. For example, before writing a function to calculate discounts, a developer would first write tests that check expected outputs for different inputs. Only then would they implement the function to satisfy those tests.

The benefits of TDD include fewer bugs, better code design, faster debugging, and greater confidence in making changes, since a suite of tests always validates the system. However, it does require discipline and can feel slower at first, though it often saves significant time during long-term maintenance.