BDD with Cucumber: A Practical Guide

Eleftheria DrosopoulouFebruary 11th, 2025Last Updated: February 7th, 2025

0 217 4 minutes read

Behavior-Driven Development (BDD) is a collaborative approach to software development that bridges the gap between technical and non-technical stakeholders. By focusing on the behavior of an application, BDD ensures that everyone involved in the project has a shared understanding of the requirements. Cucumber, a popular BDD tool, allows teams to write tests in plain language and automate them using code. This guide provides a practical introduction to BDD with Cucumber, including its benefits, how it works, and step-by-step instructions for getting started.

1. What is Behavior-Driven Development (BDD)?

BDD is an extension of Test-Driven Development (TDD) that emphasizes collaboration between developers, testers, and business stakeholders. Instead of writing tests based on technical specifications, BDD focuses on the desired behavior of the application from the user’s perspective. This approach ensures that the software meets business goals and delivers value to end-users.

1.1 Key Principles of BDD:

Collaboration: BDD encourages communication between technical and non-technical team members.
Shared Understanding: Everyone agrees on the expected behavior of the application before development begins.
Executable Specifications: Tests are written in a human-readable format and can be automated.

2. Why Use Cucumber for BDD?

Cucumber is a powerful tool for implementing BDD. It allows you to write tests in Gherkin, a plain-text language that is easy to understand for non-technical stakeholders. These tests can then be automated using programming languages like Java, Ruby, or JavaScript.

2.1 Benefits of Cucumber:

Readable Tests: Gherkin syntax uses simple keywords like Given, When, and Then to describe test scenarios.
Cross-Team Collaboration: Non-technical stakeholders can contribute to test cases.
Automation: Cucumber integrates with testing frameworks to automate the execution of test scenarios.

3. Getting Started with Cucumber

3.1 Step 1: Install Cucumber

To use Cucumber, you’ll need to install it in your project. For example, if you’re using JavaScript, you can install Cucumber via npm:

1	`npm` `install` `@cucumber/cucumber` `--save-dev`

3.2 Step 2: Write Feature Files

Feature files are written in Gherkin and describe the behavior of the application. Here’s an example of a feature file for a login functionality:

Feature: User Login
  As a user
  I want to log in to the application
  So that I can access my account
 
  Scenario: Successful login with valid credentials
    Given I am on the login page
    When I enter my username "testuser" and password "password123"
    And I click the login button
    Then I should be redirected to the dashboard

3.3 Step 3: Implement Step Definitions

Step definitions are the code that automates the steps in your feature files. Here’s an example in JavaScript:

const { Given, When, Then } = require('@cucumber/cucumber');
const assert = require('assert');
 
Given('I am on the login page', function () {
  // Code to navigate to the login page
});
 
When('I enter my username {string} and password {string}', function (username, password) {
  // Code to enter credentials
});
 
When('I click the login button', function () {
  // Code to click the login button
});
 
Then('I should be redirected to the dashboard', function () {
  // Code to verify redirection
  assert.equal(true, true); // Example assertion
});

3.4 Step 4: Run Your Tests

Once your feature files and step definitions are ready, you can run your tests using Cucumber. For example:

1	`npx cucumber-js`

4. Best Practices for BDD with Cucumber

Behavior-Driven Development (BDD) with Cucumber empowers teams to create software that aligns with business objectives by fostering collaboration and using executable specifications. To ensure success, it’s essential to follow best practices when implementing BDD. The table below provides a comprehensive overview of best practices, along with their corresponding benefits.

Best Practice	Description	Benefits
Keep Scenarios Simple	Focus each scenario on a single behavior or feature.	Easier to maintain and understand tests.
Use Descriptive Language	Write clear, concise Gherkin steps that stakeholders can easily understand.	Improves collaboration and communication across teams.
Collaborate with Stakeholders	Involve non-technical team members in writing feature files.	Ensures shared understanding of requirements.
Reuse Step Definitions	Avoid duplication by reusing common steps across scenarios.	Reduces code maintenance effort and increases efficiency.
Maintain Tests Regularly	Keep feature files and step definitions up to date as the application evolves.	Ensures tests remain relevant and accurate.
Use Tags for Test Management	Organize scenarios using tags (e.g., @smoke, @regression) for targeted test execution.	Helps manage large test suites and speeds up testing.
Write Executable Requirements	Define behavior clearly with Given-When-Then steps, linking them to business requirements.	Aligns tests closely with business goals.
Automate Test Execution	Integrate Cucumber tests with CI/CD pipelines.	Speeds up development and ensures continuous quality validation.
Optimize Step Definitions	Keep step definitions modular and DRY (Don’t Repeat Yourself).	Enhances maintainability and readability.
Leverage Reporting Tools	Use tools like Cucumber HTML Reports for detailed insights into test results.	Provides visibility into test coverage and failures.

5. Challenges of BDD with Cucumber

5.1 Learning Curve

Writing effective Gherkin scenarios and step definitions requires practice and collaboration.

5.2 Maintenance Overhead

As the application grows, maintaining feature files and step definitions can become time-consuming.

5.3 Misuse of BDD

BDD is not a silver bullet. It works best for projects with clear business requirements and active stakeholder involvement.

6. Conclusion: Is BDD with Cucumber Right for You?

Behavior-Driven Development with Cucumber is a powerful approach for building software that aligns with business goals. By fostering collaboration and providing executable specifications, BDD ensures that everyone is on the same page. Cucumber’s Gherkin syntax makes it easy to write and automate tests, making it a valuable tool for teams adopting BDD.

If your project involves complex business logic and requires close collaboration between technical and non-technical stakeholders, BDD with Cucumber is worth exploring.

BDD with Cucumber: A Practical Guide