Test-Driven Development vs Behaviour-Driven Development

Individuals working in a web development and digital marketing agency should know what is involved in testing - test-driven development (TDD) and behaviour-driven development (BDD). So, what's the deal with test-driven development vs behaviour driven development? Let's dig in and see what sets them apart.

What Is Test-Driven Development (TDD)?

Test-driven development (TDD) is a software development process that relies on automated testing. It follows the 'test-first' approach, which means writing the unit tests before writing any code. The primary objective of TDD is to facilitate the creation of clean, working code by constantly running tests and refactoring as needed.

Steps Involved in TDD

Add a test – Developers will write a test defining a function or the improvements for an existing function. Some may choose to use a modified test they have already written.
Run the test and see if it fails – This will tell the developer if the test harness (automated test framework) is functioning properly. Writing a failing test allows the developer to fix it so the code passes the test.
Write the code – Write a new code that allows it to pass the test. It may not pass perfectly, but it will be polished and finalised in the refactoring stage (5).
Run tests – This stage will determine if the new functions pass the test requirements without negatively affecting existing functions.
Refactor code – During this stage, code is constantly cleaned up and can be moved back to where it was more logically needed before it was moved for more convenient testing. Cleaning up code involves removing duplicates and clearly labelling objects, methods and classes with their current purpose while immediately running the test again to be sure functionalities are unaltered by the cleaning.
Repeat – The cycle is repeated because only 10 edits should be made in each test run. The process is repeated until the completed code passes all tests.

What Is Behaviour-Driven Development (BDD)?

BDD was first introduced by Dan North in 2006 as an extension of TDD. Its goal is to bridge the gap between business language and technical language, promoting clear communication among all team members involved in the development process.

Behaviour-driven development (BDD) is a software development process that focuses on the behaviour of the system rather than its implementation. BDD is a level 3 approach and can be considered a combination of TDD principles and the ideas set by domain-driven design and object-oriented analysis.

It allows developers to collaborate more effectively with business stakeholders and testers, leading to a better understanding of the system's requirements.

The Differences Between TDD and BDD

The main difference between TDD and BDD is their approach to testing. While both rely on automated testing, TDD focuses on unit tests, whereas BDD focuses on end-to-end tests. Unit tests in TDD are written before the code, while in BDD, they are written after the code.

Another difference between TDD and BDD is their use of language. TDD uses a technical language, whereas BDD uses a more business-friendly language. This difference is essential as it allows for better communication among team members with varying technical backgrounds.