What is Behavior Driven Development (BDD)?

Behavior-driven development (BDD) is an Agile software development methodology that encourages collaboration between developers, testers, and business stakeholders. BDD is based on the idea that the best way to ensure that software meets the needs of its users is to write tests that describe the desired behavior of the software in plain language.

What are the BDD Fundamentals ?

1. Collaboration and Communication:

   • BDD emphasizes collaboration between developers, testers, and business stakeholders.
   • Clear communication ensures all stakeholders have a shared understanding of the software requirements and behavior.

2. User Stories:

   • BDD begins with writing user stories that describe the desired behavior from an end user's perspective.
   • User stories are typically written in a standard format: "As a [role], I want [feature] so that [benefit]."

3. Scenarios and Examples:

   • Scenarios are written to illustrate specific examples of how the software should behave.
   • Each scenario consists of steps that describe the context (Given), actions (When), and expected outcomes (Then).

4. Gherkin Language:

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

5. Acceptance Criteria:

   • Scenarios serve as acceptance criteria for user stories, ensuring that all requirements are clearly defined and testable.
   • These criteria must be met for a user story to be considered complete.

6. Automated Testing:

   • BDD promotes the automation of scenarios to provide quick feedback on whether the software behaves as expected.
   • Automated tests validate that the system meets the defined behavior continuously.

Techniques of BDD

1. Three Amigos Meeting:

   • A collaborative meeting involving three key roles: a developer, a tester, and a business analyst.
   • They discuss and refine user stories, scenarios, and acceptance criteria to ensure a common understanding.

2. Example Mapping:

   • A technique to break down user stories into concrete examples.
   • Helps in identifying edge cases and creating a shared understanding of requirements.

3. Writing Gherkin Scenarios:

   • Scenarios are written in Gherkin syntax, capturing the behavior of the system in plain language.
   • 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, and others are used to automate scenarios.

   • These tools parse Gherkin syntax and map it to executable test code.

   • Example (Cucumber with Java):

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

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

   • Integrate BDD scenarios into CI/CD pipelines to ensure that automated tests are run with each build and deployment.
   • Provides rapid feedback and ensures that new changes do not break existing functionality.

6. Living Documentation:

   • BDD scenarios act as living documentation, evolving with the system and providing up-to-date information on its behavior.
   • They are easily understandable by both technical and non-technical stakeholders.

7. Refactoring:

   • Regularly review and refactor BDD scenarios and underlying test code to maintain clarity, remove redundancy, and improve maintainability.
   • Keep scenarios concise and focused on behavior rather than implementation details.

What are Benefits of BDD ?

1. Improved communication: BDD encourages communication between developers, testers, and business stakeholders. This helps to ensure that everyone is on the same page and that the software meets the needs of its users.
2. Increased collaboration: BDD encourages collaboration between developers, testers, and business stakeholders. This helps to ensure that the software is developed in a way that is efficient and effective.
3. Improved testability: BDD tests are written in plain language, which makes them easier to understand and maintain. This helps to improve the testability of the software.
4. Increased confidence: BDD tests provide a high degree of confidence that the software meets the needs of its users. This helps to reduce the risk of defects and to improve the quality of the software.

Overall, BDD is a software development process that can help to improve communication, collaboration, and testing. This can lead to the development of higher-quality software that meets the needs of the business.

What are the key principles of BDD ?

BDD is guided by several key principles that shape its approach to software development:

Collaboration: BDD encourages collaboration between different stakeholders, including developers, testers, and business representatives. By fostering open communication, BDD helps align everyone's understanding of the desired software behavior.

User Stories and Scenarios: BDD uses user stories and scenarios to define the expected behavior of the software from the end user's perspective. These scenarios, written in plain language, serve as the basis for developing and testing the application.

Gherkin Language: BDD employs the Gherkin language, a simple, human-readable syntax that allows stakeholders to describe the behavior of a system. Gherkin uses keywords like Given, When, and Then to articulate the preconditions, actions, and expected outcomes, making it accessible to non-technical team members.

Automated Testing: One of the core practices in BDD is the creation of automated tests based on the defined scenarios. These tests validate that the software behaves as specified in the Gherkin scenarios, providing rapid feedback to developers and ensuring continuous integration and delivery.

BDD Testing Tools

Here are some of the popular BDD automation tools:

1. Cucumber: Cucumber is a free and open-source BDD tool that uses the Gherkin syntax for writing test cases in plain English. It can be programmed in several languages, including Java, Ruby, and JavaScript.

2. Behave: Behave is a behavior-driven testing tool written in Python that supports the Gherkin syntax and can be used in tandem with other testing frameworks like Pytest and Unittest.

3. JBehave: JBehave is a Gherkin-based, Java-based BDD tool that supports many testing frameworks, including JUnit and TestNG.

4. SpecFlow: SpecFlow is a BDD tool that interfaces with Microsoft Studio and other .NET tools and employs the Gherkin syntax for writing specifications. It can be programmed in C# and Visual Basic, among other languages.

5. Gauge: Gauge is an open-source BDD tool that employs a markdown-based syntax to describe tests. It can be programmed in Java, Ruby, and Python, among others.

6. Reqnroll: Reqnroll is an open-source Cucumber-style BDD test automation framework for .NET.

These tools can help to streamline the testing process and improve communication between developers, testers, and stakeholders. This can help to ensure that the software meets the needs of the business and is of high quality.

Points to remember while using BDD

1. BDD is not a silver bullet: BDD is not a magic solution that will solve all of your software development problems. However, it can be a valuable tool for improving communication, collaboration, and testability.
2. BDD requires buy-in from everyone involved: BDD is most effective when everyone involved in the software development process is on board. This includes developers, testers, and business stakeholders.
3. BDD takes time to learn and implement: BDD is a new approach to software development, and it takes time to learn and implement. However, the benefits of BDD can be significant, so it is worth the investment.
4. BDD is not a replacement for other testing methods: BDD is not a replacement for other testing methods, such as unit testing and integration testing. Instead, it should be used in conjunction with these methods to improve the overall quality of the software.
5. BDD is not a replacement for other testing methods: BDD is not a replacement for other testing methods, such as unit testing and integration testing. Instead, it should be used in conjunction with these methods to improve the overall quality of the software.

Test Driven Development (TDD) vs. Behavior Driven Development (BDD) Comparison Table

Aspect	Test Driven Development (TDD)	Behavior Driven Development (BDD)
Primary Focus	Unit testing and code design	Collaboration and end-user behavior
Tests Written By	Developers	Collaboration between developers, testers, and business stakeholders
Language for Tests	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 that serve as documentation	Plain language scenarios accessible to non-technical stakeholders
Target Audience	Primarily developers	Both technical and non-technical team members
Cycle	Write tests, implement code, refactor	Define behavior, write scenarios, automate tests, validate behavior
Emphasis	Code correctness	Meeting user expectations and business goals
Collaboration	Primarily within development team	High collaboration across all stakeholders

Conclusion

In conclusion, Behavior Driven Development (BDD) is an Agile methodology that promotes collaboration, communication, and testability in software development. By focusing on user stories and scenarios written in plain language, BDD ensures that the software meets the needs of its users and aligns with business goals. BDD also encourages collaboration between developers, testers, and business stakeholders, leading to increased efficiency and effectiveness in the development process. With the use of BDD testing tools like Cucumber, Behave, JBehave, SpecFlow, Gauge, and Reqnroll, teams can streamline the testing process and improve the overall quality of the software. While BDD is not a silver bullet and requires buy-in from all involved parties, the benefits it brings make it a valuable approach to software development. So, consider adopting BDD as part of your development process to enhance communication, collaboration, and testing, ultimately leading to the delivery of high-quality software that meets the needs of your business.

FAQs about Behavior Driven Development (BDD)

1. What is Behavior Driven Development (BDD)?

Behavior Driven Development (BDD) is an Agile methodology that emphasizes collaboration among developers, testers, and business stakeholders. It focuses on writing tests that describe the desired behavior of the software in plain language, using user stories and scenarios to ensure that software development aligns with business goals.

2. What are the key principles of BDD?

BDD is guided by several principles:

• Collaboration: Encourages open communication among all stakeholders.
• User Stories and Scenarios: Defines expected behavior from the end user's perspective.
• Gherkin Language: Uses a human-readable syntax to describe behavior.
• Automated Testing: Creates automated tests based on defined scenarios to ensure continuous integration and delivery.

3. What are the benefits of BDD?

• Improved Communication: Ensures all stakeholders have a shared understanding of software behavior.
• Increased Collaboration: Promotes teamwork among developers, testers, and business stakeholders.
• Improved Testability: Tests are easier to understand and maintain.
• Increased Confidence: Provides assurance that the software meets user needs, reducing defects and improving quality.

4. What are some popular BDD tools?

• Cucumber: Uses Gherkin syntax and supports multiple languages like Java, Ruby, and JavaScript.
• Behave: A Python-based tool that supports Gherkin syntax.
• JBehave: A Java-based tool compatible with various testing frameworks.
• SpecFlow: Integrates with Microsoft Studio and other .NET tools.
• Gauge: Uses markdown syntax and supports multiple languages.
• Reqnroll: A Cucumber-style framework for .NET.

5. How does BDD differ from TDD?

While TDD focuses on writing unit tests before coding, emphasizing code correctness, BDD focuses on defining behavior from the user's perspective and ensuring software meets business goals. BDD promotes collaboration across all stakeholders and uses natural language for test scenarios, making it accessible to non-technical members.

6. Is BDD a replacement for other testing methods?

No, BDD is not a replacement but a complement to other testing methods such as unit testing and integration testing. BDD should be used in conjunction with these methods to enhance overall software quality.