What is Gherkin? Syntax, Examples, and Role in BDD

In Behavior-Driven Development (BDD), Gherkin is an important tool that bridges the gap between technical and non-technical teams. Gherkin is a simple and structured language for writing test scenarios in plain English, making it easy to understand and, more importantly, to automate your requirements. When it is combined with tools such as Cucumber helps teams define the behaviors of their software via explicit, executable specifications. In this article, we will cover what Gherkin is, its importance in BDD in general, how to write good scenarios, and best practices for writing clean, maintainable feature files.

Table of Contents:

• What is Gherkin?
• Gherkin Syntax
• Why is Gherkin Important?
• Role of Gherkin in BDD
• Writing Scenarios With Gherkin
• Gherkin Test in Cucumber
• Best Practice to Write Feature Files in BDD
• Who Can Use the Gherkin Language?
• Difference Between Gherkin and Cucumber
• Common Mistakes to Avoid in Gherkin
• Gherkin vs Traditional Test Cases
• Conclusion

What is Gherkin?

Gherkin is a plain-text language with a structured format that is used to write test cases in a human-readable format. It acts as the backbone of Behavior-Driven Development (BDD), which allows stakeholders, including developers, testers, and non-technical users, to understand application behavior without diving into complex code.

It tells us the expected behavior of a system using “Given-When-Then” scenarios written in .feature files. These descriptions can then be linked to automated tests using tools like Cucumber. Basically, Gherkin bridges the communication gap between the business and technical teams.

Gherkin Syntax

Gherkin follows a simple, consistent syntax that uses keywords such as:

• Feature: It is a high-level description of a system’s functionality.
• Scenario: It is a specific example or test case.
• Given: This is the Preconditions or initial context.
• When: It is the action taken by the user.
• Then: It is the expected outcome.
• And / But: Both are used to add multiple steps.

Example:

Feature: Login functionality

  Scenario: Successful login
    Given that the user is on the login page
    When the user enters valid credentials
    Then they should be redirected to the dashboard

Explanation: In the example, Gherkin syntax specifies a Login functionality feature with a scenario that uses the “Given-When-Then” format to illustrate the successful login process. It specifies the starting position of the user, the action they are doing, and what they should get in return. 

Why is Gherkin Important?

Gherkin is important because its structured and readable syntax makes sure that:

• Everyone speaks the same language, which means that the Business analysts, testers, and developers can collaborate effectively.
• Requirements are executable, so the written scenarios can double as both specifications and automated test cases.
• Behavior is clearly defined, which helps the teams to focus on how the system should behave from a user’s perspective.

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Role of Gherkin in BDD

Gherkin is a meaningful aspect of Behavior-Driven Development (BDD) as it provides teams with a way to express the behavior of the application in a clear and human-readable format. A few examples include:

• Gherkin serves as a translator or a bridge between business stakeholders, developers, and testers, as it supports plain language.
• It defines behavior in a structured form using the Given-When-Then scenarios of what the system does.
• When converting executable documentation into a feature file by using tools like Cucumber, it ensures the requirements are always up-to-date.
• Gherkin provides a method for better collaboration throughout the project by enabling non-technical team members to write use cases/test cases.
• Gherkin offers a method for automation by converting user stories into tests that will test behavior on a continuous basis.

In simple terms, we can conclude that the Gherkin allows BDD to be a common language for collaboration, clarity, and automation.

Writing Scenarios With Gherkin

Here are a few tips that will help you in writing scenarios with Gherkin, focusing on clarity and behavior.

• Use the “Given-When-Then” format to describe clear, behavior-focused steps. 
• Write each scenario to test an individual behavior or outcome.
• Use simple, business language, free from terms of art. 
• Use “And” or “But” to increase clarity, where it will not repeat keywords.
• Do not include any UI or implementation-specific details in the steps.
• Keep the scenarios as concise as possible as with 3 to 5 steps for better readability and clarity.
• Use Scenario Outline with Examples to efficiently test multiple data variations.
• Keep the Scenarios short and simple.

Example:

Feature: Shopping Cart

  Background:
    Given the user is logged in
    And the shopping cart is empty

  Scenario: Add a product to the cart
    When the user adds a "Laptop" to the cart
    Then the cart should contain 1 item

  Scenario: Remove a product from the cart
    Given the cart has a "Laptop"
    When the user removes the "Laptop"
    Then the cart should be empty

Explanation: In this example, “Shopping Cart” is the Gherkin feature that describes the behavior of the shopping cart, where a logged-in user can add or remove a product. The cart shows the correct number of items accordingly, and the shared login and empty cart setup is defined in the background.

Gherkin Test in Cucumber

At first, let’s know what Cucumber is, to understand how the Gherkin works in Cucumber.

Cucumber: The Cucumber is a popular BDD tool that is used to execute the Gherkin scenarios as automated tests. It basically connects the plain-text feature files that are written in Gherkin to the underlying test code through step definitions in languages such as Java, JavaScript, Python, or Ruby.

Now, we will understand how Gherkin works with Cucumber in different steps.

Step 1: Write Gherkin in a .feature file.

Example:

Feature: Login functionality

  Scenario: Successful login
    Given that the user is on the login page
    When the user enters valid credentials
    Then they should be redirected to the dashboard

Step 2: Create step definitions that link each Gherkin step to code logic.

Example:

@Given("the user is on the login page")
public void userOnLoginPage() {
    // Code to navigate to the login page
}

@When("the user enters valid credentials")
public void enterValidCredentials() {
    // Code to input valid credentials
}

@Then("they should be redirected to the dashboard")
public void verifyDashboard() {
    // Code to verify redirection
}

Step 3: Run the Test

The Cucumber reads the .feature file, then matches the steps to definitions, and at last executes the test.

Benefits of Using Cucumber with Gherkin

1. It promotes clear communication between developers, testers, and business stakeholders using plain language.
2. It allows test cases to serve as both documentation and executable tests.
3. Using Cucumber with Gherkin supports behavior-driven development by focusing on system behavior from the user’s perspective.
4. It makes test scenarios easy to understand, write, and maintain.
5. Encourages collaboration through shared feature files.
6. It integrates easily with various programming languages and testing frameworks.

Best Practice to Write Feature Files in BDD

1. Use a consistent Given-When-Then format.
2. Keep each scenario to one specific behavior.
3. Write steps in plain, business-friendly language.
4. Keep scenarios brief, simple & easy to read.
5. Use Background for common setup steps.
6. Do not duplicate the steps in any of the scenarios.
7. Focus on behavior and not implementation or UI details.
8. Use clear descriptive names for your features/scenarios.

Who Can Use the Gherkin Language?

The Gherkin language is designed for any team member of the software development helps them to be able to collaborate well, particularly in a BDD environment.

• Business analysts can use Gherkin to articulate precise, testable requirements.
• Product owners can use Gherkin to ensure that the software behavior aligns with business objectives.
• Testers/QA engineers can use Gherkin to write the automated acceptance tests.
• Developers can use Gherkin to bridge the feature file and test code to the step definitions.
• Non-technical stakeholders can read and comprehend scenarios without the need to know how to code.

Difference Between Gherkin and Cucumber

Although Gherkin and Cucumber are closely related in Behavior-Driven Development (BDD), they have different purposes. Here is the comparison table that shows the difference between Gherkin and Cucumber.

Common Mistakes to Avoid in Gherkin

1. Applying technical or implementation-level steps.
2. Assembling lengthy, complex scenarios with too many steps.
3. Reworking the similar steps in different scenarios.
4. Packaging several behaviors in one scenario.
5. Using ambiguous or vague language in the steps.
6. Ignoring the Given-When-Then format.
7. Repeating the setup steps rather than using Background.
8. Adding UI or low-level system details to scenarios.

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Gherkin vs Traditional Test Cases

Here is a comparison table that helps you to understand the difference between Gherkin and traditional test cases in an efficient manner.

Conclusion

Gherkin is not just a syntax; it’s a collaboration tool. It allows cross-functional teams to describe the behavior of software by using a language that everyone understands. Even when combined with tooling, such as Cucumber, Gherkin provides automation and clarity to the software development process so that everyone can work together toward delivering business value.

What is Gherkin? – FAQs