10 Karate Framework Interview Questions and Answers

The Karate Framework is a powerful tool for API testing, combining API test-automation, mocks, performance-testing, and even UI automation into a single, unified framework. Its simplicity and ease of use make it an attractive choice for developers and testers alike, allowing for efficient and effective testing processes. With its expressive syntax and comprehensive feature set, Karate enables teams to write tests that are both readable and maintainable.

This article aims to prepare you for interviews by providing a curated selection of questions and answers related to the Karate Framework. By familiarizing yourself with these examples, you will gain a deeper understanding of the framework’s capabilities and be better equipped to demonstrate your proficiency during technical discussions.

Karate Framework Interview Questions and Answers

1. Explain the primary use cases for the Karate Framework and how it differs from other API testing tools.

The primary use cases for the Karate Framework include:

• API Testing: Karate is designed for testing web APIs, allowing users to write tests in a simple, readable syntax. This makes it suitable for testing RESTful services, SOAP services, and GraphQL APIs.
• Behavior Driven Development (BDD): Karate integrates with BDD practices, enabling teams to write tests in a Gherkin-like syntax. This promotes collaboration between developers, testers, and business stakeholders.
• Data-Driven Testing: Karate supports data-driven testing, allowing users to parameterize tests and run them with different data sets.
• Mocking and Stubbing: Karate provides support for mocking and stubbing APIs, useful for testing in isolation by simulating dependencies on external services.

Karate differs from other API testing tools in several ways:

• Unified Framework: Karate offers a unified framework for API, UI, and performance testing, reducing the complexity of managing multiple tools.
• Scriptless Testing: Karate’s syntax is simple and readable, allowing users to write tests without needing to learn a programming language.
• Built-in Assertions: Karate includes a rich set of built-in assertions and matchers, simplifying the test writing process.
• Seamless Integration: Karate integrates well with CI/CD pipelines and other testing tools, ensuring tests are run automatically as part of the development process.

2. Write a simple Karate script to send a GET request to an API endpoint and validate the response status code is 200.

To write a simple Karate script to send a GET request to an API endpoint and validate the response status code is 200, you can use the following example:

Feature: Validate GET request

  Scenario: Send GET request and validate response status code
    Given url 'https://api.example.com/endpoint'
    When method GET
    Then status 200

3. How do you perform JSON schema validation in Karate? Provide an example.

JSON schema validation in Karate ensures that the JSON data structure conforms to a predefined schema. This is useful for validating API responses to ensure they meet the expected format and data types.

Example:

Feature: JSON Schema Validation

  Scenario: Validate JSON Schema
    Given url 'https://api.example.com/data'
    When method get
    Then status 200
    And match response == { id: '#number', name: '#string', active: '#boolean' }

4. Demonstrate how to use data-driven testing in Karate by writing a script that reads test data from a CSV file.

Data-driven testing involves storing test data in external files or databases, allowing test scripts to read this data to execute test cases. This approach separates test logic and test data, making it easier to manage and maintain tests. Karate supports data-driven testing by allowing test data to be read from various sources, including CSV files.

Example:

Feature: Data-Driven Testing with CSV

  Background:
    * def testData = read('classpath:testData.csv')

  Scenario Outline: Test with data from CSV
    Given url 'https://api.example.com'
    And path 'endpoint'
    And param id = <id>
    When method get
    Then status 200
    And match response == <expectedResponse>

    Examples:
      | testData |

5. Explain how to mock an API endpoint in Karate and provide a sample script.

Mocking an API endpoint in Karate involves creating a mock server to simulate the behavior of a real API. This is useful for testing when the actual API is unavailable or when specific scenarios need to be tested. Karate provides built-in support for creating mock servers using the karate-config.js file and the karate object.

Example:

// karate-config.js
function fn() {
  var config = {
    baseUrl: 'http://localhost:8080'
  };

  karate.configure('mock', {
    path: '/api/v1/users',
    method: 'get',
    response: {
      status: 200,
      body: [
        { id: 1, name: 'John Doe' },
        { id: 2, name: 'Jane Doe' }
      ]
    }
  });

  return config;
}

6. Create a Karate script that includes conditional logic based on the response of an API call.

In Karate, conditional logic can be implemented using the if statement to handle different scenarios based on the response of an API call. This is useful for making decisions within your test scripts.

Example:

Feature: Conditional Logic Example

  Scenario: Conditional logic based on API response
    Given url 'https://jsonplaceholder.typicode.com/posts/1'
    When method get
    Then status 200
    * def responseStatus = response.status
    * if (responseStatus == 200) {
    *   print 'Status is 200, proceeding with further checks'
    *   match response.id == 1
    * } else {
    *   print 'Status is not 200, handling error'
    *   match response.error == 'Not Found'
    * }

7. How do you define and use custom JavaScript functions within a Karate test? Provide an example.

In Karate, you can define and use custom JavaScript functions to extend the capabilities of your tests. This is useful for performing complex operations or calculations not directly supported by Karate’s built-in functions.

Example:

// Define a custom JavaScript function
function add(a, b) {
    return a + b;
}

// Save the function in a file named 'custom-functions.js'
karate.defineFunction('add', add);

In your Karate test script, you can then use the custom function as follows:

Feature: Using custom JavaScript functions in Karate

Scenario: Add two numbers using a custom function
    * def add = read('classpath:custom-functions.js')
    * def result = add(5, 3)
    * match result == 8

8. Explain how you would perform security testing for an API using Karate.

Karate supports various types of testing, including security testing. To perform security testing for an API using Karate, you can leverage its built-in support for HTTP calls, JSON and XML assertions, and scripting capabilities.

Example:

Feature: Security Testing for API

  Scenario: Test for SQL Injection
    Given url 'http://example.com/api/resource'
    And request { id: '1 OR 1=1' }
    When method GET
    Then status 400

  Scenario: Test for Authentication
    Given url 'http://example.com/api/secure-resource'
    And header Authorization = 'Bearer invalid_token'
    When method GET
    Then status 401

  Scenario: Test for Authorization
    Given url 'http://example.com/api/admin-resource'
    And header Authorization = 'Bearer valid_user_token'
    When method GET
    Then status 403

9. How do you handle authentication mechanisms (e.g., OAuth, JWT) in Karate?

Karate provides built-in support for handling various authentication mechanisms, including OAuth and JWT. This is achieved through its configuration capabilities and the use of custom headers.

Example for OAuth:

Feature: OAuth Authentication

  Background:
    * def accessToken = call read('classpath:oauth-token.feature')

  Scenario: Access secured endpoint
    Given url 'https://api.example.com/secure-endpoint'
    And headers { Authorization: '#(accessToken)' }
    When method get
    Then status 200

Example for JWT:

Feature: JWT Authentication

  Background:
    * def jwtToken = 'your-jwt-token-here'

  Scenario: Access secured endpoint
    Given url 'https://api.example.com/secure-endpoint'
    And headers { Authorization: 'Bearer #(jwtToken)' }
    When method get
    Then status 200

10. How do you handle file uploads and downloads in Karate? Provide an example.

In Karate, handling file uploads and downloads is straightforward. Karate provides support for multipart file uploads and downloading files as part of its HTTP capabilities.

Example of file upload:

Feature: File Upload Example

  Scenario: Upload a file
    Given url 'http://example.com/upload'
    And multipart file myFile = { read: 'path/to/file.txt', filename: 'file.txt' }
    When method post
    Then status 200

Example of file download:

Feature: File Download Example

  Scenario: Download a file
    Given url 'http://example.com/download'
    When method get
    Then status 200
    And def responseBytes = response
    And karate.write(responseBytes, 'path/to/save/file.txt')