Karate Framework for API tests

Karate is a relatively new open source framework for testing Web services. Even though Karate is written in Java, its main value proposition is that testers don’t need to do any Java programming in order to write fully automated tests. Instead, testers use a Gherkin-like language with steps for making requests and validating responses. It’s like Cucumber with out-of-the-box Web API steps! There are a bunch of other nifty features, too.

This article is my quick-start guide for Karate. As a prerequisite, make sure you understand how Web services work (like REST APIs). Knowing BDD will also help.

Project Setup

I created my Karate project using the Maven archetype since I am quite familiar with Maven. I named my project “firstchop”:

mvn archetype:generate \

  -DarchetypeGroupId=com.intuit.karate \

  -DarchetypeArtifactId=karate-archetype \

  -DarchetypeVersion=0.9.0 \

  -DgroupId=com.automationpanda \

  -DartifactId=firstchop

The directory layout was standard for Java Maven / Cucumber-JVM projects. (In fact, Karate was based on Cucumber-JVM until version 0.8.0.) Interestingly, the Karate docs recommend placing feature files under src/test/java instead of src/test/resources.

The Examples

The archetype project included example tests in the users.feature file. The first scenario from the file, copied below, tests getting users from the JSONPlaceholder REST API:

Feature: sample karate test script

 

Background:

  * url 'https://jsonplaceholder.typicode.com'

 

Scenario: get all users and then get the first user by id
 
  Given path 'users'
  When method get
  Then status 200
 

  * def first = response[0]
  Given path 'users', first.id
  When method get
        

  Then status 200

All steps are quite concise. The Java implementation is essentially hidden from the tester (unless, of course, they want to plunge into the framework’s lower levels). Furthermore, this scenario shows how to use data from one response as the input for a second request.

Running Tests

Since I chose to use Maven and InteliJ, the easiest way to run tests without any additional configuration was through the command line using “mvn test”. The example tests came with an ExamplesTest.java file that will run all feature files in the package when it is discovered during Maven’s “test” phase.

Karate can generate helpful test reports, too. The project generates JUnit reports by default, but other report formats like Cucumber reports are also possible. The JUnit HTML report shows a step-by-step log for each scenario.

Full requests and responses are automatically logged, which is great for debugging.

Analysis

Overall, Karate is a great tool for testing Web services. It handles all of the programming implementation details so that testers can focus more on testing. Its syntax is concise, clear, and versatile. Its native support for JSON object makes request and response handling feel natural. The GitHub docs are on-point. Anyone testing REST APIs should give it serious consideration.

It simply leverages the strengths of Cucumber – readability, reusability, and tooling – to make automated Web service testing easier. Its Gherkin keywords simply provide structure and familiarity to its steps. And it’s perfectly okay that Karate isn’t “pure BDD”.

With that said, I would argue that a tester probably needs basic programming skills to be successful with Karate. Execution needs Java setup no matter what, and feature files are really just fancy test scripts.