Behavior Driven Development: Beginner's Guide to Collaboration

What is Behavior Driven Development (BDD)?

Behavior Driven Development (BDD) is an Agile methodology that emphasizes collaboration among developers, testers, and business stakeholders. It ensures that software meets users' needs by writing tests that describe the desired behavior in plain language. This approach encourages clear communication and shared understanding of software requirements, ultimately leading to better quality and more maintainable code.

BDD Fundamentals

1. Collaboration and Communication:

   • BDD fosters close collaboration among developers, testers, and business stakeholders.
   • Open communication ensures that everyone has a shared understanding of the requirements and desired behavior.

2. User Stories:

   • BDD starts with user stories written from the perspective of the end user, typically formatted as:
     "As a [role], I want [feature] so that [benefit]."

3. Scenarios and Examples:

   • Detailed scenarios illustrate specific behaviors of the software using the Given-When-Then format.
   • These scenarios serve as clear acceptance criteria that define when a user story is complete.

4. Gherkin Language:

   • BDD employs Gherkin, a simple, human-readable syntax that uses keywords like Given, When, Then, And, and But to structure scenarios.

5. Acceptance Criteria:

   • Scenarios double as acceptance criteria, ensuring all functional requirements are testable and clearly defined.

6. Automated Testing:

   • Automation of BDD scenarios provides rapid feedback on software behavior and ensures continuous validation throughout the development cycle.

Techniques of BDD

1. Three Amigos Meetings:

   • A collaborative session involving a developer, tester, and business analyst to discuss and refine user stories and scenarios, ensuring alignment across teams.

2. Example Mapping:

   • A technique to break down user stories into concrete examples, helping to identify edge cases and clarify requirements.

3. Writing Gherkin Scenarios:

   • Scenarios are written in Gherkin syntax. For example:

     Scenario: User logs in successfully
       Given the user is on the login page
       When the user enters valid credentials
       Then the user should be redirected to the dashboard

4. Automating Scenarios with BDD Tools:

   • Tools like Cucumber, SpecFlow, Behave, JBehave, Gauge, and Reqnroll parse Gherkin syntax and link it to executable test code. For example, using Cucumber with Java:

     @Given("the user is on the login page")
     public void userIsOnLoginPage() {
         // Navigate to login page
     }
     
     @When("the user enters valid credentials")
     public void userEntersValidCredentials() {
         // Enter credentials
     }
     
     @Then("the user should be redirected to the dashboard")
     public void userIsRedirectedToDashboard() {
         // Verify dashboard redirection
     }

5. Continuous Integration (CI) and Continuous Delivery (CD):

   • BDD scenarios are integrated into CI/CD pipelines to run automated tests with every build, ensuring that new changes do not break existing functionality.

6. Living Documentation:

   • BDD scenarios act as up-to-date documentation that evolves with the system, making it accessible and understandable to both technical and non-technical stakeholders.

7. Refactoring:

   • Regular review and refactoring of scenarios and test code help maintain clarity and reduce redundancy while keeping tests focused on behavior rather than implementation details.

Benefits of BDD

• Improved Communication:
  Facilitates a shared understanding among all team members, ensuring the software meets user expectations.
• Increased Collaboration:
  Encourages cross-functional teamwork, aligning development with business goals.
• Enhanced Testability:
  Scenarios written in plain language are easier to understand, maintain, and automate.
• Increased Confidence:
  Provides assurance that the software behaves as expected, reducing defects and enhancing overall quality.

BDD Testing Tools

Popular BDD tools include:

• Cucumber:
  An open-source tool that uses Gherkin syntax, supporting multiple programming languages such as Java, Ruby, and JavaScript.

• Behave:
  A Python-based BDD tool that leverages Gherkin syntax to create test scenarios.

• JBehave:
  A Java-based tool that integrates with frameworks like JUnit and TestNG.

• SpecFlow:
  A BDD tool for .NET that uses Gherkin syntax and integrates with Microsoft Studio.

• Gauge:
  An open-source tool that uses a markdown-based syntax and supports multiple languages.

• Reqnroll:
  A Cucumber-style framework for .NET that facilitates BDD testing.

Points to Remember When Using BDD

1. BDD is Not a Silver Bullet:
   While BDD improves communication and testability, it is not a one-size-fits-all solution.

2. Team Buy-In is Essential:
   BDD works best when all stakeholders—from developers to business analysts—are fully engaged.

3. Learning Curve:
   Adopting BDD requires time and training, but the long-term benefits make the investment worthwhile.

4. Complementary, Not a Replacement:
   BDD should be used alongside other testing methods such as unit and integration testing to ensure comprehensive software quality.

TDD vs. BDD Comparison Table

Aspect	Test Driven Development (TDD)	Behavior Driven Development (BDD)
Primary Focus	Unit testing and code correctness	Collaboration and end-user behavior
Tests Written By	Developers	Developers, testers, and business stakeholders
Test Language	Programming language of the application	Natural language (Gherkin syntax)
Testing Levels	Primarily unit testing	Acceptance, integration, and system testing
Tools	JUnit, pytest, NUnit	Cucumber, SpecFlow, Behave
Documentation	Code-focused tests	Plain language scenarios accessible to non-technical stakeholders
Target Audience	Primarily developers	Both technical and non-technical team members
Workflow Cycle	Write tests, implement code, refactor	Define behavior, write scenarios, automate tests, validate behavior
Emphasis	Code correctness	Meeting user expectations and business goals
Collaboration	Within the development team	Across all stakeholders

Conclusion

Behavior Driven Development (BDD) is a collaborative Agile methodology that improves communication among developers, testers, and business stakeholders. By focusing on user stories and scenarios written in plain language, BDD ensures that software meets real user needs and business objectives. With the support of BDD tools like Cucumber, Behave, and SpecFlow, teams can automate tests, integrate them into CI/CD pipelines, and maintain living documentation of system behavior. Although BDD requires commitment and may involve a learning curve, its benefits in improving collaboration, testability, and software quality make it a valuable addition to modern development practices.

FAQs about Behavior Driven Development (BDD)

1. What is Behavior Driven Development (BDD)?

BDD is an Agile methodology that uses plain language to describe the desired behavior of software, promoting collaboration among developers, testers, and business stakeholders.

2. What are the key principles of BDD?

• Collaboration: Engaging all stakeholders.
• User Stories and Scenarios: Defining requirements from the user’s perspective.
• Gherkin Language: Using simple syntax to structure scenarios.
• Automated Testing: Validating behavior continuously.

3. What are the benefits of BDD?

BDD enhances communication, increases collaboration, improves testability, and builds confidence in software quality by ensuring it meets user needs.

4. Which tools are popular for BDD?

Popular tools include Cucumber, Behave, JBehave, SpecFlow, Gauge, and Reqnroll.

5. How does BDD differ from TDD?

While TDD focuses on writing unit tests for code correctness, BDD emphasizes defining behavior in natural language and fostering collaboration to ensure the software aligns with business goals.

6. Is BDD a replacement for other testing methods?

No, BDD complements methods like unit and integration testing to enhance overall software quality.