By David Kidd
11/215/2023

Origins

Gherkin is a domain-specific language (DSL) used primarily in Behavior-Driven Development (BDD) to write clear and structured acceptance criteria. It was introduced alongside tools like Cucumber, which was created in 2008 by Aslak Hellesøy. Gherkin's primary goal is to bridge the communication gap between technical and non-technical stakeholders by providing a simple, human-readable format that can also serve as executable tests.

Inspired by Agile methodologies and the principles of Test-Driven Development (TDD), Gherkin evolved as a natural extension of these practices, emphasizing collaboration and shared understanding. It allows teams to define features based on user behavior, focusing on the "what" rather than the "how."

Benefits of Gherkin-Style Acceptance Criteria

Improved Collaboration Across Teams

• Gherkin promotes clear communication between developers, testers, product managers, and business stakeholders. By using plain English in a structured format, everyone can understand and contribute to the criteria, regardless of technical expertise.
• This format ensures that the entire team is aligned on expectations, reducing misunderstandings and rework.

Executable Specifications

• Gherkin criteria can be directly tied to automated tests using tools like Cucumber, SpecFlow, or Behave. This dual purpose—serving as both documentation and test scripts—saves time and ensures that the implementation remains in sync with the requirements.

Focus on User Behavior

• The Given-When-Then structure emphasizes user behavior and outcomes, keeping the focus on delivering value. Instead of describing system details, Gherkin criteria describe how the system should behave in real-world scenarios.

Scalable and Reusable

• Gherkin scenarios are modular and can be reused across different features or projects. For instance, a login scenario might be applicable across multiple applications or systems.

Clarity and Precision

• The structured format reduces ambiguity. Each step in a Gherkin scenario corresponds to a specific action, making it easy for developers to understand what needs to be implemented and for testers to know what to validate.

Encourages Test-First Development

• By defining Gherkin acceptance criteria before implementation, teams adopt a shift-left approach, catching potential issues earlier in the development cycle and fostering a culture of test-first or behavior-driven development.

Supports Continuous Integration and Deployment (CI/CD)

• Automated Gherkin-based tests integrate seamlessly into CI/CD pipelines, ensuring that features meet their acceptance criteria throughout the development lifecycle.

Enhances Stakeholder Engagement

• Non-technical stakeholders can participate in defining and reviewing Gherkin scenarios. This inclusivity ensures that requirements align with business goals and customer needs.

Traceability and Documentation

• Gherkin scenarios provide a living document that evolves alongside the software. As scenarios are tied to automated tests, they remain relevant and up-to-date, offering traceability for features and requirements.

Promotes Consistency

• The standardized format ensures that all acceptance criteria across the project are written in a consistent way, making it easier to review and understand.

Origins of the "Given-When-Then" Syntax

The Given-When-Then syntax was influenced by a technique called Specification by Example (SBE), which focuses on using concrete examples to clarify requirements. It aligns with the practices of BDD, which prioritizes collaboration and shared understanding. The syntax was intentionally designed to be intuitive:

• Given: Describes the initial context or preconditions.
• When: Describes the action or event being tested.
• Then: Describes the expected outcome or behavior.

This structure mirrors how people naturally describe scenarios, making it intuitive and easy to adopt.

Challenges and Limitations

While Gherkin offers many benefits, it’s not without challenges:

• Learning Curve: Teams unfamiliar with BDD or Gherkin syntax may require training.
• Overhead: Writing and maintaining Gherkin scenarios can add upfront effort, particularly for small or simple projects.
• Misuse: If not written collaboratively, Gherkin scenarios can become overly technical or deviate from their user-centric purpose.

Conclusion

Gherkin-style acceptance criteria revolutionize how teams define and validate requirements by making them more collaborative, testable, and user-focused. Originating from BDD practices, Gherkin has become a staple for teams striving to improve software quality and bridge gaps between technical and business perspectives. When used effectively, it not only enhances the development process but also ensures that the delivered product aligns closely with user and business needs.