Demystifying Cucumber BDD: Bridging the Gap Between Specification and Automation

 

Cucumber is a tool widely used for Behavior-Driven Development (BDD) that enables collaboration between developers, testers, and non-technical stakeholders in software development. BDD is an approach that emphasizes communication and collaboration among team members by using natural language specifications that describe the behavior of a system. Cucumber uses the Gherkin language to express these specifications in a readable and understandable format.

Key Concepts:

1. Feature Files:

• Feature files are written in Gherkin syntax and contain scenarios describing the behavior of the application. Each feature file typically corresponds to a specific feature or user story.
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2. Feature: Login functionality Scenario: User logs in with valid credentials Given the user is on the login page When the user enters valid username and password Then the user should be logged in successfully

Gherkin Syntax:

• Gherkin is a plain-text language that uses keywords like Feature, Scenario, Given, When, and Then to describe the behavior of the system in a human-readable format.
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Given the user is on the login page When the user enters valid username and password Then the user should be logged in successfully

Step Definitions:

• Step definitions are implemented in programming languages like Java, Ruby, or Python. They provide the actual automation code that corresponds to each step in the Gherkin scenarios.

import io.cucumber.java.en.Given; import io.cucumber.java.en.When; import io.cucumber.java.en.Then; public class StepDefinitions { @Given("the user is on the login page") public void navigateToLoginPage() { // Implementation to navigate to the login page } @When("the user enters valid username and password") public void enterValidCredentials() { // Implementation to enter valid credentials } @Then("the user should be logged in successfully") public void verifyLoginSuccess() { // Implementation to verify successful login }

}

Cucumber Runner:

• The Cucumber runner is responsible for executing the Gherkin scenarios and linking them to the corresponding step definitions. It acts as the entry point for running Cucumber tests.

import io.cucumber.junit.Cucumber; import io.cucumber.junit.CucumberOptions; import org.junit.runner.RunWith; @RunWith(Cucumber.class) @CucumberOptions(features = "src/test/resources/features", glue = "stepDefinitions") public class TestRunner { // This class is empty }

Workflow:

1. Write Feature Files:

   • Define the behavior of the application in Gherkin syntax within feature files.

2. Implement Step Definitions:

   • Write step definitions in a programming language to automate the behavior described in feature files.

3. Run Cucumber Tests:

   • Execute Cucumber tests by running the Cucumber runner. Cucumber will parse the feature files, match steps with step definitions, and execute the automation code.

4. Review Results:

   • Review the test results, which are presented in a human-readable format. Cucumber generates reports indicating the status of each scenario and step.

Cucumber promotes collaboration and ensures that the behavior of the application is clearly defined and validated through automated tests. It encourages a shared understanding of features among team members and helps maintain a living documentation of the application's behavior.

Cucumber official website