Quick and Easy Introduction to Test-Driven Development (TDD)

Test-Driven Development (TDD) is a software development approach that follows a simple yet powerful iterative cycle:

• Red: Write a failing test.
• Green: Write the code necessary to make the test pass.
• Refactor: Refactor the code for better design while applying the knowledge acquired in the process ensuring that all tests continue to pass.
• Iterate this cycle Red > Green > Refactor as needed.

Ensuring Code Quality: Writing the tests first?

One of the fundamental principles of TDD is writing tests before writing code, which may seem counterintuitive at first.

However, the goal should not be starting soon, but rather delivering earlier with more confidence and more quality. This approach promotes better and sooner conversations with all stakeholders involved so that you gain clarity on what your code should accomplish and can better structure your solution accordingly, leading to better code quality by prompting developers to consider the desired behavior of their code before implementation.

In essence, you are first building your safety net against regressions when making changes in the future, and as a result, your code becomes more reliable, maintainable, and resistant to bugs.

Tests are live documentation

Tests serve as live documentation, accurately describing the expected behavior of the code. This documentation reduces the learning curve for new team members, increases team confidence when introducing changes, and facilitates debugging and behavior clarifications.

Fostering continuous improvement and adaptability

The iterative nature of TDD encourages developers to embrace change and seek feedback at every stage of development.

Each iteration provides valuable insights into the code's design, functionality, and usage by the end users, allowing for continuous refinement and optimization.?

Another benefit is that TDD is the best vaccine against technical debt. Not only because with every iteration you will be minimizing the technical debt that you are accumulating, but also you enable you to make any refactor you might need to do with a high level of confidence safety net already built up.

TDD in practice

Adopting TDD is really easy, it just requires being open to new ways of working and? being willing to give it a try and therefore being willing to build a new habit.

You can see the benefits from the first iteration when you apply TDD, but also be certain that those benefits will be piling up with time. The more you apply TDD, the better your team will become.

Just define, measure and keep track of some key metrics applicable to your project, whether it is story points delivered per sprint or deployments in production, number of bugs, delivery time, predictability…

At least that has happened to me every time my team changed to TDD in the past 10 years.

To Know more

• "Test-Driven Development: By Example" by Kent Beck
• What is TDD? By Agile Alliance

What is your experience with TDD?