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  • Writer's pictureCraig Risi

The Pros and Cons of Different API Test Tools – RestAssured

There are many different types of APIs out there, but if you as an organization are dealing with only REST-based APIs, then RestAssured may be a tool worth considering. While it might be limited in its focus on the REST API protocol, it makes up for it with incredible simplicity in the sending of handling responses and validating API endpoints' behaviors in a way that makes testing and automation quite easy to set up.

Developed by Johan Haleby and was first released in 2010. It was initially designed to provide a simpler and more concise way of testing RESTful APIs in Java. However, seeing a need for a tool that would make API testing more developer-friendly and efficient, led to a more customized and automated approach that formed the foundation of the RestAssured tool.

Over the years, RestAssured has gained in popularity within the Java and API testing communities due to its ease of use, expressive syntax, and powerful capabilities. The library quickly became a go-to choice for testing RESTful APIs, especially in the context of Test-Driven Development (TDD) and Behaviour-Driven Development (BDD) practices, thanks to work done to integrate these methodologies into the core toolset.

Being an open-source tool and quickly gaining support from the developer community has helped the tool continue to grow in the functionality it offers, stay relevant as new trends and best practices emerged in API testing, and allowed for integration with many commonly used tools. However, the core simplicity and focus on the REST protocol have remained. Recent updates making it arguably simpler to use than ever, with output and code that is incredibly readable even for the non-developer.

Here are some key features and functionalities of RestAssured:

  • Fluent and Easy-to-Read Syntax: RestAssured provides a fluent and intuitive syntax that makes writing tests straightforward and easy to read, allowing testers and developers to focus on the test logic rather than boilerplate code.

  • HTTP Methods Support: It supports all standard HTTP methods such as GET, POST, PUT, DELETE, etc., enabling you to interact with different endpoints and APIs effectively.

  • Request Specification: You can set up common request configurations like base URI, headers, query parameters, and authentication details using the Request Specification feature. This allows you to reuse these settings across multiple test cases.

  • Response Validation: RestAssured enables you to validate various aspects of the API response, such as status codes, headers, response body, JSON/XML payload, and response time.

  • JSON and XML Support: RestAssured has built-in support for parsing and validating JSON and XML responses, which is especially useful when testing APIs that return data in these formats.

  • Support for Authentication: It supports various types of authentication methods like Basic Authentication, OAuth, and Bearer Token, making it suitable for testing APIs with different security mechanisms.

  • Integrations: RestAssured can be easily integrated with popular testing frameworks like JUnit and TestNG, allowing seamless integration of API tests with your existing test suite.

  • Assertion Libraries: It provides support for various assertion libraries like Hamcrest and TestNG Assertions, enabling you to choose the one that fits your testing requirements.

It’s light on features compared to some of the other API testing tools, but when it comes to automation, it is often considered a lot easier to us and work with – especially in integrating your tests directly into existing frameworks and pipelines.

To get started with RestAssured, you need to set up the library as a dependency in your Java project. Then, you can begin writing test cases using RestAssured's fluent API to send requests, handle responses, and perform validations.

To showcase its simplicity, below is a sample of how a simple test would work given a typical BDD approach which I highlighted previously in the analysis of Cucumber.

import org.testng.annotations.Test;

import static io.restassured.RestAssured.*;

public class MyAPITest {


public void testGetUser() {



.header("Authorization", "Bearer YOUR_ACCESS_TOKEN")






.body("name", equalTo("John Doe"))

.body("email", equalTo(""));



In this example, the test case sends a GET request to the "/users/123" endpoint, sets the base URI and authorization header, and then validates the response's status code, content type, and specific fields in the JSON response.

Pros of RestAssured:

  • Easy-to-Read and Expressive Syntax: RestAssured provides a fluent and intuitive API, making it easy to read and write test cases. Testers and developers can quickly understand the test logic without getting bogged down by boilerplate code.

  • JSON and XML Support: It has built-in support for handling JSON and XML responses, which are commonly used data formats in modern APIs. This makes parsing and validating responses straightforward.

  • Request and Response Specification: RestAssured allows you to set up common configurations for requests and responses, promoting code reusability and maintainability.

  • HTTP Method Support: It supports all standard HTTP methods, making it suitable for testing various API endpoints and behaviors.

  • Powerful Validation: RestAssured offers extensive validation options, enabling testers to verify different aspects of the API response, such as status codes, headers, and response payloads.

  • Integration with Testing Frameworks: It integrates well with popular Java testing frameworks like JUnit and TestNG, allowing seamless integration of API tests into existing test suites.

  • Authentication Support: RestAssured supports different types of authentication mechanisms, such as Basic Authentication and OAuth, which is crucial when testing secure APIs.

  • Open Source and Active Community: Being an open-source project, RestAssured benefits from an active community that continuously contributes to its development, provides support, and helps address issues.

  • Extensible: RestAssured can be extended with custom filters and plugins, enabling users to add additional functionality or integrations as needed.

Cons of RestAssured:

  • Java-Centric: RestAssured is primarily focused on Java, which may not be ideal for teams working with other programming languages. While there are bindings for other languages, they may not have the same level of maturity and support.

  • Overhead for Simple Tests: For very simple API tests, RestAssured's expressive syntax might be seen as overkill, and testers might prefer simpler tools or libraries.

  • High level of abstraction: The overall tests might be easy to script, but there is a fair amount of overhead required to keep other libraries maintained.

  • Performance for Large Tests: In some cases, especially when dealing with large test suites, the expressive syntax and configuration options might introduce some performance overhead.

  • Focus on only REST protocol: RestAssured is specifically designed for API testing and the REST protocol and while it can work with other API protocols, you would need to do additional work to do this effectively. lacks built-in support for UI testing, which might require additional tools and integrations.

Reasons for choosing RestAssured

  • REST-based API applications with a testing team that features strong development skills – or a development team that is very hands-on with testing.

  • You are comfortable working with open-source solutions as an organization.

  • You don’t need your API testing to be highly performant.

If you’re looking for a simple way to get your REST API tests automated, then Rest Assured is certainly one of the best options out there. It might not be as comprehensive as the previous tools we looked at in Postman and SoapUI, but its simplicity is one of the things that makes it popular and easy to get the job done from an automation perspective.


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