Top Cucumber Interview Questions and Answers

What is Cucumber?

Cucumber is a widely used testing framework based on the Behavior-Driven Development (BDD) methodology. It allows you to write automated acceptance tests in a plain-text format (using the Gherkin language), making them easily understandable by both technical and non-technical stakeholders. Cucumber is often integrated with tools like Selenium for web application testing.

Cucumber's Programming Language

Cucumber itself is written in Ruby, but it supports many programming languages for implementing the test steps (Java, .NET, Python, etc.).

Purpose of Behavior-Driven Development (BDD)

BDD aims to improve communication and collaboration among project stakeholders (developers, testers, business analysts) by using a shared, understandable language to describe software functionality. This helps ensure that the software meets the business requirements.

Gherkin Language in Cucumber

Cucumber uses Gherkin, a business-readable domain-specific language (DSL), to write test scenarios. Gherkin uses keywords like Feature, Scenario, Given, When, Then, and And to describe the software's behavior.

Files Needed to Run Cucumber Tests

• Feature files (*.feature): Contain the test scenarios written in Gherkin.
• Step definition files: Contain the code (in a supported language) that implements the steps defined in the feature file.

Feature Files in Cucumber

Feature files provide high-level descriptions of the software's functionality. Each feature file typically describes a specific feature of the application. A feature file contains one or more scenarios.

Cucumber Scenario Keywords

• Given: Sets up the initial context for a scenario.
• When: Describes the action or event.
• Then: Specifies the expected outcome.
• And: Used to add additional steps to Given, When, or Then.

Background in Cucumber

The Background keyword in a feature file allows you to define steps that are executed before each scenario within that feature file. This is useful for setting up common preconditions.

Scenario Outlines in Cucumber

Scenario outlines enable you to run the same scenario with multiple sets of input data using placeholders (parameters). The Examples keyword defines the data sets.

Step Definitions in Cucumber

Step definitions are the code that implements the steps described in the feature file. They use regular expressions to match the steps, execute the corresponding code, and verify the results.

Programming Languages Supported by Cucumber

Cucumber supports multiple programming languages for implementing step definitions, including Java, .NET, Ruby, and others.

JBehave vs. Cucumber

Regular Expressions in Cucumber

Regular expressions (regex) are used in step definitions to match the text of the steps in the feature file. They provide a flexible way to define patterns and handle variations in step text.

Software for Running Cucumber Web Tests

• Cucumber
• Ruby (and its development kit)
• An IDE (like ActiveState)
• A web automation tool (like Selenium or Watir)
• (Optional) Ansicon and RSpec

Advantages of the Cucumber Framework

• Open-source and free.
• Easy-to-understand, plain-text format.
• Improved communication between technical and non-technical stakeholders.
• Easier to maintain and update tests.
• Good integration with other tools.

Test Harness in Cucumber

A test harness provides a structured way to run Cucumber tests. It separates setup, execution, and cleanup logic, making tests easier to manage and maintain.

RSpec vs. Cucumber

Selenium

Selenium is a popular tool for automated testing of web applications.

Selenium vs. Cucumber

Why Use Cucumber with Selenium?

Cucumber enhances Selenium by providing a more human-readable and understandable way to write and manage tests (using Gherkin). This improves collaboration between technical and non-technical team members.

Step Definitions

Step definitions link Gherkin steps to actual code that interacts with the application under test.

Maximum Number of Scenarios in a Feature File

While there's no strict limit, it's best practice to keep the number of scenarios in a single feature file manageable (around 10) to improve readability and maintainability.

Behavior-Driven Development (BDD) Methodology

BDD uses a shared language (Gherkin) to define software behavior, improving collaboration between developers, testers, and business stakeholders.

Test-Driven Development (TDD)

TDD (Test-Driven Development) is a software development approach where tests are written *before* the code. The process typically involves writing a failing test, writing the minimum code to pass the test, then refactoring the code.

TDD Process

1. Write a test case (that initially fails).
2. Run the tests (to confirm failure).
3. Write the code to pass the test.
4. Run the tests again (to confirm success).
5. Refactor the code (to improve readability and maintainability).
6. Repeat for new test cases.

BDD (Behavior-Driven Development) and TDD: Similarities

BDD and TDD share similarities: Both are iterative development approaches, emphasize writing tests before code, and use automated tests to ensure code quality. Both aim to improve software quality and reduce bugs.

BDD vs. TDD: Key Differences

Cucumber Dry Run

A Cucumber dry run compiles your feature files and step definitions to identify any syntax errors or mismatches *without* actually executing the tests. This helps catch problems early in the development process.

TestRunner Class in Cucumber

The TestRunner class acts as the entry point for executing Cucumber tests. It connects the feature files (containing test scenarios in Gherkin) to the step definition files (containing the code that implements the steps). The TestRunner class itself typically contains minimal code (annotations).

package com.sample.TestRunner;

import org.junit.runner.RunWith;
import cucumber.api.CucumberOptions;
import cucumber.api.junit.Cucumber;

@RunWith(Cucumber.class)
@CucumberOptions(features = "src/test/resources/features", glue = {"stepDefinitions"})
public class Runner {}
        

Code in TestRunner Class

It's generally recommended to keep the TestRunner class simple, primarily containing the @RunWith and @CucumberOptions annotations to configure Cucumber's execution.

Feature File Execution Starting Point

When using Cucumber with Selenium, the TestRunner class serves as the starting point for executing your feature files.

@CucumberOptions Tag

The @CucumberOptions annotation configures Cucumber's test execution. Key parameters include:

• features: Specifies the path to your feature files.
• glue: Specifies the path to your step definition files.

@CucumberOptions(
    features = "src/test/resources/features",
    glue = "stepDefinitions"
)
        

Build Tools Integration with Cucumber

• Gradle
• Maven

Hooks in Cucumber

Hooks in Cucumber are blocks of code that run before or after certain events (like scenarios). They're useful for setup (e.g., opening a browser) and cleanup (e.g., closing the browser) tasks.

Feature: Invoice Generation

  Scenario: Generate PDF Invoice
    Given the user is on the invoice page
    Then a PDF invoice is generated

  Scenario: Verify Invoice Fields
    Given the invoice is opened
    Then the payment amount is displayed
        

import cucumber.api.java.en.*;
import cucumber.api.java.*;

public class InvoiceValidation {
    @Given("^the user is on the invoice page$")
    public void user_is_on_invoice_page() { ... }

    @Then("^a PDF invoice is generated$")
    public void pdf_invoice_generated() { ... }
    // ... other step definitions ...

    @Before
    public void setUp() { ... } // Runs before each scenario

    @After
    public void tearDown() { ... } // Runs after each scenario
}