10 Karate API Testing Interview Questions and Answers

Karate API Testing is an open-source framework designed for testing web services and APIs. It simplifies the process of creating and executing automated tests by combining API testing, mocking, and performance testing into a single, cohesive tool. With its easy-to-understand syntax and powerful capabilities, Karate has become a popular choice for developers and testers aiming to ensure the reliability and performance of their APIs.

This article offers a curated selection of interview questions and answers focused on Karate API Testing. By familiarizing yourself with these questions, you will gain a deeper understanding of the framework and be better prepared to demonstrate your expertise in API testing during your interview.

Karate API Testing Interview Questions and Answers

1. How would you perform a simple GET request to an API endpoint using Karate?

To perform a simple GET request to an API endpoint using Karate, define a feature file with the necessary steps. Karate uses a Gherkin-like syntax to describe API interactions, making tests easy to read and write.

Example:

Feature: Simple GET request example

  Scenario: Perform a GET request to an API endpoint
    Given url 'https://jsonplaceholder.typicode.com'
    And path 'posts/1'
    When method get
    Then status 200
    And print response

This feature file defines a scenario where a GET request is made to the endpoint ‘https://jsonplaceholder.typicode.com/posts/1’. The response status is checked to ensure it is 200 (OK), and the response is printed.

2. How do you send a POST request with a JSON payload in Karate?

Sending a POST request with a JSON payload in Karate involves defining the URL, setting the request payload, and sending the POST request.

Example:

Feature: Send POST request with JSON payload

  Scenario: Send POST request
    Given url 'https://example.com/api'
    And request { "key1": "value1", "key2": "value2" }
    When method post
    Then status 200

Here, the Given keyword sets the URL, And request sets the JSON payload, and When method post sends the POST request. The Then status 200 checks that the response status is 200.

3. How can you extract and validate specific fields from a JSON response in Karate?

Karate’s built-in JSON path syntax and validation methods make extracting and validating specific fields from a JSON response straightforward.

Example:

Feature: Extract and Validate JSON Fields

  Scenario: Extract and validate specific fields from JSON response
    Given url 'https://api.example.com/data'
    When method get
    Then status 200
    And match response.name == 'John Doe'
    And match response.age == 30
    And match response.address.city == 'New York'

The match keyword validates specific fields in the JSON response. The response keyword holds the JSON response, and JSON path syntax is used to access specific fields.

4. Explain how you can parameterize a Karate test to run with multiple sets of data.

Parameterization in Karate allows running the same test scenario with different data sets, useful for testing various input combinations. This is achieved using the Scenario Outline and Examples keywords.

Example:

Feature: Parameterized API Test

  Scenario Outline: Test with multiple data sets
    Given url 'https://api.example.com/resource'
    And request { "param1": "<param1>", "param2": "<param2>" }
    When method post
    Then status 200
    And match response == { "result": "<expectedResult>" }

  Examples:
    | param1 | param2 | expectedResult |
    | value1 | value2 | result1        |
    | value3 | value4 | result2        |
    | value5 | value6 | result3        |

The Scenario Outline defines a template, and the Examples section provides different data sets. Each row in the Examples table represents a different set of parameters for the Scenario Outline.

5. What are some common assertions you can use in Karate to validate API responses?

Common assertions in Karate validate various aspects of API responses, ensuring expected behavior and correct data. These include:

• Equality Assertion: Checks if the response data matches the expected value.
• Schema Validation: Ensures the response adheres to a predefined JSON schema.
• Contains Assertion: Verifies the response contains specific data or elements.
• Size Assertion: Checks the size of arrays or collections in the response.
• Status Code Assertion: Validates the HTTP status code of the response.

Example:

Feature: API Testing with Karate

Scenario: Validate API Response
  Given url 'https://api.example.com/data'
  When method get
  Then status 200
  And match response == { id: 1, name: 'John Doe' }
  And match response.name == 'John Doe'
  And match response contains { id: 1 }
  And match response.id == 1
  And match response.size() == 2

6. How do you perform authentication (e.g., Basic Auth, OAuth) in Karate?

Authentication in Karate can be performed using methods like Basic Auth and OAuth. Karate provides built-in support for these mechanisms.

Example for Basic Auth:

Feature: Basic Auth Example

  Background:
    * url 'https://api.example.com'
    * configure headers = { Authorization: 'Basic ' + karate.base64('username:password') }

  Scenario: Get user details
    Given path 'user', 'details'
    When method get
    Then status 200

Example for OAuth:

Feature: OAuth Example

  Background:
    * url 'https://api.example.com'
    * def accessToken = call read('classpath:oauth-token.feature')
    * configure headers = { Authorization: 'Bearer ' + accessToken }

  Scenario: Get user details
    Given path 'user', 'details'
    When method get
    Then status 200

7. Explain the use of tags in Karate and how they help in organizing tests.

Tags in Karate categorize and manage test cases, making it easier to run specific subsets of tests. They can group tests based on functionality, priority, or environment.

Example:

Feature: User API Tests

  @smoke
  Scenario: Verify user creation
    Given url 'https://api.example.com/users'
    When method post
    Then status 201

  @regression
  Scenario: Verify user deletion
    Given url 'https://api.example.com/users/1'
    When method delete
    Then status 200

You can run tests with specific tags using the command line:

mvn test -Dkarate.options="--tags @smoke"

This command runs only the tests tagged with @smoke.

8. How do you handle file uploads and downloads in Karate?

Handling file uploads and downloads in Karate is straightforward due to its support for multipart file uploads and response handling.

Example for file upload:

Feature: File Upload

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

Example for file download:

Feature: File Download

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

9. How can you integrate Karate tests into a CI/CD pipeline?

Integrating Karate tests into a CI/CD pipeline involves several steps to automate test execution as part of your build and deployment process:

• Set Up Your CI/CD Tool: Choose a tool like Jenkins, GitLab CI, CircleCI, or Travis CI.
• Configure Your Project: Ensure your project is set up to run Karate tests, typically with a Maven or Gradle build file.
• Write Your Karate Tests: Develop your test scripts and store them in an accessible directory.
• Create a CI/CD Pipeline Configuration: Define a pipeline configuration file specifying the steps to build your project and run the tests.
• Run Tests as Part of the Pipeline: Include a step to execute the Karate tests using a command like mvn test or gradle test.
• Report and Monitor Results: Configure your CI/CD tool to capture and report test results, including generating reports and sending notifications for failures.

10. How do you create and use reusable features in Karate?

Reusable features in Karate promote code reusability and maintainability by defining common functionalities in separate feature files. These can be called from other feature files using the call or callonce keyword.

Example:

Reusable feature file (common.feature):

Feature: Common reusable steps

  Scenario: Set base URL
    * url 'https://api.example.com'

  Scenario: Authenticate user
    * def authToken = 'Bearer abc123'
    * header Authorization = authToken

Main feature file (test.feature):

Feature: Test API with reusable features

  Background:
    * call read('common.feature@Set base URL')
    * call read('common.feature@Authenticate user')

  Scenario: Get user details
    Given path 'user', 'details'
    When method get
    Then status 200

The common.feature file contains reusable steps for setting the base URL and authenticating the user. The test.feature file calls these steps using the call keyword, making the test script more concise and easier to maintain.