What is behavior-driven development (BDD)?

Table of Contents

• Introduction
• How BDD Works
  • 1. Collaboration and Shared Understanding
    • Example:
  • 2. The BDD Cycle
  • 3. Using Gherkin Language in BDD
    • Example of Gherkin:
  • 4. Automation and BDD Tools
• Benefits of BDD
  • 1. Enhanced Collaboration
  • 2. Focus on User Behavior
  • 3. Improved Test Coverage
  • 4. Readable and Maintainable Tests
• Practical Example: BDD in Action
  • Step 1: Write the Behavior Scenario
  • Step 2: Write the Code to Pass the Test
  • Step 3: Refactor and Iterate
• Conclusion

Introduction

Behavior-Driven Development (BDD) is an agile software development methodology that encourages collaboration between developers, testers, and non-technical stakeholders. It focuses on defining the behavior of an application through examples written in natural language. BDD emphasizes the importance of communication and shared understanding, ensuring that the application behaves as expected according to business requirements.

BDD extends the idea of Test-Driven Development (TDD) by making tests more readable and aligned with business goals. The tests in BDD are usually written in a simple, descriptive language, making them accessible to all project participants, not just developers.

How BDD Works

1. Collaboration and Shared Understanding

BDD emphasizes communication between various stakeholders, including developers, testers, and business analysts. The goal is to ensure that everyone has a clear understanding of the application’s expected behavior. By focusing on the desired behavior from the perspective of the user, BDD allows teams to create features that directly meet the business goals.

In BDD, user stories or features are written in a way that describes how the software should behave under certain conditions. This description is typically done using a Given-When-Then format, which helps structure the behavior clearly.

Example:

2. The BDD Cycle

The BDD cycle is similar to the Red-Green-Refactor cycle in TDD but with a focus on behavior rather than just functionality. Here’s a breakdown of the BDD process:

• Define the behavior: Work with stakeholders to write the expected behavior of the application using examples and scenarios.
• Write failing tests: Write tests based on the defined behavior. These tests initially fail because the functionality hasn't been implemented yet.
• Implement code: Develop the feature or functionality to meet the defined behavior and pass the test.
• Refactor and iterate: Once the tests pass, refactor the code if needed to ensure it is maintainable and efficient.

3. Using Gherkin Language in BDD

BDD typically uses a domain-specific language called Gherkin to write behavior scenarios in a readable, plain-text format. This language is structured in the Given-When-Then format and serves as a way to describe test cases in business terms.

Example of Gherkin:

4. Automation and BDD Tools

BDD can be integrated into automated testing using tools like Cucumber (for Java and other languages) or Jasmine (for JavaScript). These tools parse the Gherkin language and automate the testing process based on the scenarios written. Developers then implement the steps in the language of their choice.

Benefits of BDD

1. Enhanced Collaboration

BDD promotes collaboration between technical and non-technical team members by using a shared language and ensuring everyone understands the desired behavior. This reduces miscommunication and helps align the development process with business needs.

2. Focus on User Behavior

By concentrating on the behavior of the system rather than the underlying code, BDD ensures that features are built with the end-user experience in mind. This leads to software that meets customer needs more effectively.

3. Improved Test Coverage

Since BDD emphasizes writing tests based on behavior scenarios, it naturally leads to better test coverage. Each scenario covers a specific use case, ensuring that the application behaves as expected across different conditions.

4. Readable and Maintainable Tests

The natural language format of BDD scenarios makes tests easier to read and maintain. Non-technical stakeholders can easily understand the tests, making it simpler to verify that the application behaves correctly.

Practical Example: BDD in Action

Let’s say you’re building a shopping cart feature. The goal is to ensure that when a user adds an item to the cart, it appears correctly.

Step 1: Write the Behavior Scenario

Step 2: Write the Code to Pass the Test

In a BDD framework like Cucumber or Jasmine, developers would implement the steps in the programming language they’re using:

Step 3: Refactor and Iterate

After implementing the code to pass the test, you can refactor it if necessary, ensuring the functionality is optimized and clean.

Conclusion

Behavior-Driven Development (BDD) enhances collaboration between teams by focusing on defining and testing the behavior of the software in plain language. By using scenarios written in formats like Given-When-Then, BDD ensures that the software’s features meet user expectations and business requirements. The practice encourages communication, leading to better alignment and higher-quality software. Through tools like Cucumber, BDD can be integrated into the software development lifecycle, making testing more structured and efficient.