What is The Difference Between TDD and BDD?

DILSHA K K | December 29, 2022

What is The Difference Between TDD and BDD?

Test-driven development (TDD) is a development technique that focuses more on the implementation of a feature. Behavior-driven development (BDD) is a development technique that focuses on the system's behavior. Let’s have a look at the difference between TDD and BDD.

Test-Driven Development (TDD)

Test-driven development is an iterative development process. In TDD, developers write tests before writing enough production code to satisfy those tests and subsequent refactoring. Developers use the specs and first write tests that describe the behavior of the code. It's a short cycle of testing, coding, and refactoring.

The key ingredient for being effective with test-driven development is understanding what it truly is.TDD means letting your tests drive your development (and your design). This can be done in unit tests, functional tests, and acceptance tests. Since you're checking behavior instead of testing a code, you'll usually end up writing a very different type of test that is more resilient to future changes.

Advantages of TDD

In comparison to older methods, test-driven development produces high-quality applications in a shorter amount of time. To successfully implement TDD, developers and testers need to accurately predict how the application and its features will be used in the real world.

1. Better Program Design and Higher Code Equality

When writing a test, the programmer should first define the goal that the piece of code wants to achieve. Developers will appreciate the experience it provides and its consistency with the rest of the code overall. Developers think of everything from interfaces to work plans.

2. Detailed Project Documentation

When writing tests against a particular requirement, programmers quickly create rigorous, detailed specifications. All possible user actions are already included. Thus, we already have a scenario that determines the future. It saves users and programmers additional work by not having to create complex documentation.

3. TDD Speeds up the Project Development Process Time

When writing code without using TDD, it takes time for programmers to understand whether the code works correctly. In test-driven development, developers quickly realize that something is wrong when a test should pass. As a result, time is saved during the development phase of the project, and teams can quickly fix code if they detect code corruption.

4. Code Flexibility and Easier Maintenance

Refactoring, part of the TDD process, is about optimizing existing code to make it easier to read and implement. Promotes clean and attractive code structure. Even if you're not a developer, you may be able to read the code and understand its message.

Disadvantages of TDD

1. No Silver Bullet

Testing can help you find bugs, but they can't find bugs that you just put in your test and implementation code. If you don't understand the problem you're trying to uncover, writing a test is most likely useless.

2. Slow Process

Once you start using TDD, simple implementations can seem time-consuming. Before you can finally start writing code, you need to believe in an interface, write test code, and run tests.

3. Team Members have to do it Together

TDD affects code planning, so we recommend that all members of your team use TDD, or none at all. And to this day, sometimes it's hard to justify TDD to management. Because half the time developers write code that doesn't show up in the product, they often feel it takes longer to implement the latest features. It helps when the whole team agrees on the importance of unit testing.

Behavior-Driven Development (BDD)

Behavior Driven Development (BDD) is a software development approach that evolved from TDD (Test Driven Development). It differs in that it is written in a common language, improving communication between technical and non-technical teams and stakeholders. In both development approaches, tests are written before the code, but in Behavior Driven Development (BDD) tests are more user-centric and based on system behavior.

Advantages of BDD

Software design in BDD begins with acceptance tests. Stakeholders and the development team, serve as the base for communication.

1. Strong Collaboration

With BDD, all the involved parties have a strong understanding of the project and they can all have a role in communication and constructive discussions. BDD increases and improves collaboration. It makes it simple for all project participants to interact with the product development cycle. And by using plain language, all can write behavior scenarios.

2. High Visibility

Everyone has a clear understanding of how the project is progressing because a universal language is used.

3. The Software Design Follows Business Value

The value and demands of the business are highly valued by BDD. By setting priorities with the client, based on the value it provides, developers can provide a better result because they have a strong understanding of how the client thinks. By concentrating on the value, no pointless features are constructed.

4. The Ubiquitous Language

The ubiquitous language is understandable by all the members of the team, which reduces misconceptions and misunderstandings and makes it easier for new members to join the working process.

5. More Confidence from the Developers' Side

In general, teams using BDD are more confident that they haven't broken their code and are more predictable when it comes to their work.

6. Lower Costs

By improving the quality of the code, you are reducing the costs of maintenance and minimizing the project’s risks.

Disadvantages of BDD

  • Before you can use BDD, you need to understand the concept of TDD.
  • Behavior-driven development is incompatible with the waterfall approach.
  • Testers using BDD should have sufficient technical expertise.
  • If the requirements aren't carefully established, BDD might not work.

What is the Difference between TDD and BDD?

The main difference between TDD and BDD is that TDD focuses on individual units or features of the application whereas BDD focuses on the application as a whole.

Stands for Test Driven Development. Stands for Behavior Driven Development.
The process begins with creating a test case. The process begins by creating a scenario according to the expected behavior.
The process begins by creating a scenario according to the expected behavior. BDD focuses on making applications work for the end user.
Test instances are written in programming languages. The scenarios are written in plain English, making them easier to read than TDD.
Changes in how applications work have a major impact on TDD test cases. BDD scenarios are not significantly impacted by feature changes.
Changes in how applications work have a major impact on TDD test cases. BDD scenarios are not significantly impacted by feature changes.
Collaboration is only required between developers. Collaboration is required between all the stakeholders.
May be a better approach for projects involving the API and 3rd party tools. May be a better approach for user action driven projects. Example: e-commerce website, application system, etc.
Tests in TDD can only be understood by anyone without programming knowledge. BDD tests can be understood by anyone, even those with no programming knowledge.
TDD reduces the chance of bugs in your tests. Bugs in tests are harder to track down than in TDD.

We hope this blog has clarified your doubts about TDD and BDD! There are many things to consider when choosing between TDD and BDD. BDD is regarded by some as a better means of finding bugs, whereas TDD is considered to provide greater code coverage by others. It is not possible to choose between the two methodologies. Choosing a methodology depends on the individual and the project team. Please don't hesitate to ask if you have any questions, our experts will be happy to assist you.

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