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REST Assured vs Postman – Top Key Differences, Examples

June 17, 2024Raunak Jain
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Rest Assured vs Postman
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In the world of API testing, tools like REST Assured and Postman have become indispensable allies for developers and testers alike. Both REST Assured and Postman offer robust features and functionalities that streamline the process of testing APIs and ensuring their reliability. 

REST Assured is an open-source Java-based testing library designed for automating REST API testing. On the other hand, Postman is a popular, user-friendly API development and testing tool that provides a comprehensive environment for designing, testing, and documenting APIs.

However, when choosing the right tool for your specific needs, it’s essential to understand the differences between REST Assured and Postman. In this article, we will delve into the topic of REST Assured vs Postman. By the end, you’ll have a clear picture of the strengths and weaknesses of REST Assured and Postman, enabling you to make an informed decision on which tool aligns best with your API testing requirements.

What is REST Assured?

REST Assured is a powerful open-source Java library designed for automating and simplifying the testing of RESTful APIs. It provides a simple, intuitive way to validate and interact with RESTful web services. REST Assured is particularly popular among developers and testers for its ability to make HTTP requests, validate responses, and perform various assertions on the data. 

This library is often integrated into Java-based test frameworks, allowing testers and developers to automate the testing of APIs effectively. REST Assured supports various authentication methods, request and response customization, and JSON/XML parsing, making it a versatile tool for API testing.

Highlighting Features of REST Assured

Here are a few highlighting features of REST Assured that make it one of the key candidates for API testing.

  • Simplicity: It provides a simple and intuitive syntax for making HTTP requests and verifying API responses. It reduces the complexity of writing API tests in Java, making it accessible to developers and testers of varying skill levels.
  • Request Customization: With REST Assured, you can easily customize HTTP requests by specifying parameters, headers, authentication details, and other properties, giving you full control over the requests sent to the API.
  • Response Validation: It offers extensive support for response validation, allowing you to verify status codes, response headers, and response body content with ease.
  • JSON and XML Support: REST Assured simplifies working with JSON and XML responses, offering built-in methods for parsing and validating data in these formats.
  • Test Framework Integration: You can seamlessly integrate REST Assured with popular Java testing frameworks like JUnit and TestNG, allowing for structured and organized testing.
  • Authentication Options: REST Assured supports various authentication methods, including basic authentication, OAuth, and API key authentication, making it versatile for testing APIs with different security measures.
  • Modular and Extensible: It enables the creation of modular and maintainable API tests, thanks to its support for code organization and extensibility.
  • Reporting: REST Assured can be integrated with reporting tools to generate comprehensive reports and logs, aiding in result analysis and debugging.
  • Response Time Validation: It allows for response time measurements, enabling testers to check the performance of the API under different conditions.
  • Integration with Continuous Integration (CI) Systems: REST Assured can be seamlessly integrated into CI/CD pipelines, ensuring that API tests are automated and run as part of the deployment process.

Example of API Testing using REST Assured

Here’s a simple example of testing a RESTful API using REST Assured in Java. In this example, we will send an HTTP GET request to an API endpoint, retrieve the response, and perform basic validations on the response.

<styled-code>
import io.restassured.RestAssured;
import io.restassured.response.Response;
import org.testng.annotations.Test;

public class RestAssuredExample {

    @Test
    public void testGetRequest() {
        // Define the base URI of the API
        RestAssured.baseURI = "https://jsonplaceholder.typicode.com";

        // Send an HTTP GET request to the "/posts/1" endpoint
        Response response = RestAssured.get("/posts/1");

        // Validate the HTTP status code (e.g., 200 OK)
        int statusCode = response.getStatusCode();
        System.out.println("Status Code: " + statusCode);
        assert statusCode == 200;

        // Validate the response body (e.g., check if it contains specific data)
        String responseBody = response.getBody().asString();
        System.out.println("Response Body: " + responseBody);
        assert responseBody.contains("id\": 1");

        // Additional validations can be added as needed
    }
}
</styled-code>

In this example:

  • We set the base URI for the API we want to test using RestAssured.baseURI.
  • We send an HTTP GET request to the “/posts/1” endpoint using RestAssured.get().
  • We retrieve the HTTP status code and response body from the Response object.
  • We perform basic assertions to check if the status code is 200 (OK) and if the response body contains the expected data.

What is Postman?

Postman

Postman is a widely acclaimed API testing tool that provides a user-friendly, collaborative platform for designing, testing, and documenting APIs. It is available as a web application and a desktop client, catering to developers, testers, and even non-technical users who work with APIs. 

Postman allows users to create and send HTTP requests, including RESTful requests, and receive responses in a visually appealing interface. It also offers features for writing tests and scripts, managing collections of API requests, and sharing API documentation. Postman simplifies API testing by offering a graphical user interface, which makes it accessible to a wide range of professionals involved in API development and testing.

Key Features of Postman API Platform

Here are a few key features of Postman that make it a versatile and indispensable tool for professionals working with APIs.

  • Graphical User Interface (GUI): Postman offers an easy-to-use GUI that enables users to create and manage API requests visually, eliminating the need to write complex code for basic API testing.
  • Request Building: Users can create various types of HTTP requests (GET, POST, PUT, DELETE, etc.) and customize them with headers, parameters, and request bodies.
  • Collections: Postman allows users to organize API requests into collections, making it convenient to group related endpoints for testing and documentation purposes.
  • Testing and Automation: Postman includes a powerful testing framework that allows users to write test scripts in JavaScript, ensuring that API responses meet expected criteria. These scripts can be automated and run as part of the testing process.
  • Environment Variables: Users can set up environment variables to manage different configurations for testing, making it easy to switch between development, staging, and production environments.
  • Sharing and Collaboration: Postman supports collaboration by enabling users to share collections, tests, and documentation with team members. It fosters teamwork and knowledge sharing.
  • Pre-built Integrations: Postman provides integrations with popular services, allowing users to test and validate APIs that interact with third-party tools and services seamlessly.
  • Monitoring and Mocking: Postman offers tools for monitoring APIs in real-time and mocking endpoints, which is particularly useful for simulating API behavior during development.
  • Documentation Generation: It can automatically generate documentation for your APIs based on the requests and tests you create, making it easier for others to understand and utilize your APIs.
  • Automated Testing in CI/CD: Postman can be integrated into continuous integration and continuous deployment (CI/CD) pipelines to automate API testing as part of the development and deployment process.
  • Security Testing: Postman supports API security testing, including OAuth and JWT token handling, helping ensure that your APIs are secure and compliant.

API Testing Example Using Postman

Here are step-by-step instructions on how to perform API testing in Postman.

API Testing Example Using Postman
  1. Open Postman: Launch the Postman application or access it through the postman web version
  2. Create a New Collection:
  • In the left sidebar, click on “Collections.”
  • Click the “New Collection” button and give it a name, such as “Country API Test.”
  1. Create a New Request:
  • Inside your collection, click the “Add a request” button.
  • Name your request, for example, “Get Country Data.”
  1. Set Request Details:
  • In the newly created request, choose the request type from the dropdown (e.g., GET).
  • Enter the API endpoint URL in the request URL field. You can use a sample API like “https://restcountries.com/v3/region/europe.
  1. Send the Request: Click the “Send” button to send the request.
  2. View the Response: In the lower part of the window, you’ll see the response from the API. It’s usually in JSON format.
  3. Add Tests:
  • Click the “Tests” tab just above the response.
  • In the “Tests” tab, you can create simple tests without writing code. For example:
    • To check the status code, use the “Status code: Code is 200” snippet.
    • To validate if the response is JSON, use the “Response body: JSON value check” snippet.
    • To check if the response contains a specific value, use the “Response body: Response contains string” snippet.
  1. Run the Tests:
  • Click the “Send” button again to run the tests.
  • Postman will execute the tests and display the results in the “Test Results” tab.
  1. Review Test Results:
  • In the “Test Results” tab, you’ll see which tests passed and which tests failed, along with a summary of the test results.
  1. Monitor and Share: 
  • Postman provides a comprehensive test report, showing which tests passed or failed. 
  • You can share the collection with your team by clicking the “Share” button in the top-right corner of the Postman window, allowing them to run the same tests and review the results.

Why REST-assured is preferable over Postman for Test Automating?

REST Assured and Postman are both valuable tools for API testing, but the preference for REST Assured over Postman for test automation is justified. With REST Assured, you can code your tests in Java and deploy them to run them automatically. On the other hand, Postman is mostly used for manual and exploratory testing as it’s a no-code platform.

REST Assured is a Java-based library, and if your development and testing stack predominantly revolves around Java, it offers seamless integration with your existing codebase. If your API testing requirements are highly specific or complex, REST Assured’s flexibility can be a significant advantage.

When API tests are written as code using REST Assured, they can be stored in version control systems like Git. This facilitates collaboration and versioning, allowing teams to work together on the same test suites, track changes, and maintain test scripts over time.

REST Assured is well-suited for handling complex scenarios, such as dynamic data-driven tests, handling large datasets, and conditional logic in test scripts. While Postman also offers scripting capabilities, REST Assured’s Java foundation provides extensive flexibility for complex testing scenarios.

However, it’s essential to note that the preference for REST Assured or Postman can vary based on team expertise, project requirements, and the specific context of your API testing needs. Postman remains a powerful tool, particularly when you want to perform quick ad-hoc tests, create detailed documentation, or involve non-technical stakeholders in the API testing process. 

In many cases, organizations use both tools in tandem, with Postman for exploration and manual testing and REST Assured for robust, automated testing within their Java-based environments. The choice ultimately depends on what aligns best with your development and testing workflows.

Why is the Postman Tool Preferable?

While REST Assured may be preferable over Postman due to its Java language compatibility, Postman is also a highly preferable tool for many individuals and teams, especially in the context of API development and testing, for several compelling reasons.

With its visual interface for creating and managing API requests, Postman eliminates the need for in-depth coding knowledge, enabling anyone to interact with APIs and run tests. It is exceptional for quickly creating and testing API requests. It allows developers and testers to prototype and explore APIs effortlessly. 

You can easily build requests, add parameters, and view responses in a visually appealing format, which is particularly useful during the initial stages of API development. Moreover, Postman also provides scripting capabilities using JavaScript, which allows for more advanced testing and automation.

It enables the organization of API requests into collections and the management of different environments. This simplifies test management by allowing users to group related requests and switch between different testing configurations easily. It generates interactive and well-structured API documentation automatically based on the requests and tests you create.

All in all, Postman’s preference is rooted in its user-friendly approach, efficient workflow, and versatility for both manual and automated API testing. It is an ideal choice for teams looking to streamline their API development and testing processes, especially when not all team members have extensive coding expertise.

Postman vs REST Assured: Key Highlights

Let’s discuss a few key differences highlighting the distinct strengths and use cases of Postman vs REST Assured.

FeaturePostmanREST Assured
User InterfaceGUI-based with no coding requiredCode-based, Java library for automation
Scripting CapabilitiesJavaScript scripting for testingJava-based, offers full programming flexibility
Manual TestingIdeal for ad-hoc and manual testingPrimarily focused on automated testing
API DocumentationAuto-generates interactive documentationLacks built-in documentation generation
Environment ManagementProvides environment variables and switchingCan define configurations but lacks native environment management
CollaborationSupports team collaboration and sharingRequires version control for team collaboration
Continuous IntegrationIntegration options available, but not as seamlessEasily integrated into CI/CD pipelines for automated testing
Complex Testing ScenariosSuitable for basic to intermediate scenariosProvides advanced options for handling complex scenarios
PlatformAvailable as a web app and desktop clientJava-based, compatible with different platforms
Learning CurveLow, suitable for non-technical usersSteeper learning curve, more suitable for developers and testers

Postman vs REST Assured: In-Depth Comparison

In this in-depth comparison of Postman and REST Assured, we will explore the key differences between these two popular tools for API testing and why you might choose one over the other.

User Interface vs. Code-Based Automation

  • Postman: Postman offers a user-friendly graphical user interface (GUI) that simplifies API testing for a wide range of users. Its point-and-click approach allows for quick request creation, making it ideal for manual and exploratory testing.
  • REST Assured: In contrast, REST Assured is code-based and Java-centric. While this provides extensive flexibility for automation and advanced scripting, it does require programming knowledge, making it better suited for developers and testers comfortable with coding.

Manual Testing vs. Automated Testing

  • Postman: It excels at manual testing and exploratory testing. It provides a platform for easily crafting and executing ad-hoc API requests, making it accessible for non-technical team members and testers who may not be well-versed in coding.
  • REST Assured: It is primarily designed for automated testing. It allows developers to write code to automate API tests, and it integrates well with continuous integration (CI) systems, making it a powerful choice for test automation within the development pipeline.

Scripting Capabilities

  • Postman: It offers JavaScript scripting capabilities, enabling users to write custom tests and automate API interactions. This provides a balance between no-code testing and script-based testing.
  • REST Assured: It is fully code-based and provides extensive scripting capabilities in Java. This means you can implement complex test scenarios, including data-driven tests and custom assertions.

API Documentation Generation

  • Postman: One of Postman’s notable features is its ability to automatically generate interactive API documentation. This simplifies the process of sharing API information and usage instructions with team members and external stakeholders.
  • REST Assured: REST Assured doesn’t offer built-in documentation generation. Users need to rely on other documentation tools or manual efforts to create API documentation.

Environment Management

  • Postman: Postman provides an environment feature that allows you to manage different testing configurations and switch between them easily. This is particularly useful for testing in various environments (e.g., development, staging, production).
  • REST Assured: While REST Assured doesn’t have a native environment management feature, you can define configurations programmatically, but it may require more manual setup.

Collaboration and Version Control

  • Postman: It supports collaboration with team members and allows you to share collections, tests, and documentation. However, it’s less integrated with version control systems.
  • REST Assured: It relies on version control systems for collaboration and versioning of test code. This can be beneficial for organizations with established version control practices.

Continuous Integration (CI) Integration

  • Postman: It offers integration options for CI/CD pipelines but may require additional setup for seamless automation.
  • REST Assured: It is easily integrated into CI/CD pipelines, allowing automated API testing as an integral part of the development and deployment process.

Learning Curve

  • Postman: It has a low learning curve and is accessible to non-technical users. It’s a great choice for teams with a mix of technical and non-technical members.
  • REST Assured: It has a steeper learning curve, as it requires proficiency in Java and automation testing concepts. It is better suited for developers and dedicated testers with programming skills.

Alternative for REST Assured and Postman

Alternative for REST Assured and Postman

Testsigma is an AI-powered, cloud-based test automation tool that provides a compelling alternative to both REST Assured and Postman for API testing and broader test automation needs. 

Testsigma combines the ease of use and collaborative features of Postman with the automation capabilities of REST Assured, offering a comprehensive platform for automated testing. With Testsigma, you can create and execute API tests without the need for extensive coding, thanks to its natural language-based test creation approach using simple English. 

Check out this guide on how to import your test cases from Postman to Testsigma.

Here are a few reasons why you should consider Testsigma as your go-to test automation tool.

  • Easy Test Automation: It offers an easy and intuitive way to automate tests in simple English without any coding knowledge.
  • All-in-one Testing: With Testsigma, you can perform RESTful API testing, automated web UI/UX testing, cross-browser testing, etc. in 3000+ devices in the Cloud and locally.
  • Multi-Platform Support: It allows users to automate their tests for web, mobile, API, and desktop applications from the same platform.
  • AI-Supported Features: Testsigma includes AI-supported built-in features that help users save time on their test maintenance, such as automatic script maintenance, bug reporting, and test optimization.
  • Cloud Execution: It offers easy and efficient test execution on the cloud on more than 3000+ browser and device combinations, enabling users to run their tests from anywhere at any time.
  • Debugging Made Easy: Testsigma offers several debugging features, including the ability to capture screenshots, videos, and logs during test runs.
  • Customizable Reports: Users can choose which real-time metrics to report on and how to format the reports.
  • Collaborative Setup: The platform also integrates with popular CI/CD tools, making it easy to incorporate test automation into existing workflows.
  • Parallel Testing: It supports parallel testing, which can significantly reduce testing time.
  • Testing on Local Devices: Testsigma allows users to test their apps on local devices, which can help identify issues that may not be present in a simulated environment.
  • Data-Driven Testing: It supports data-driven testing, allowing users to test their apps with a variety of data inputs.
  • Image Recognition: Testsigma includes image recognition capabilities, which can help identify visual changes to an app.
  • 24/7 Support: Testsigma offers round-the-clock support to users, ensuring that any issues or questions are addressed promptly.

Try out Testsigma today with a free trial.

Here

Conclusion

In conclusion, the choice between Postman and REST Assured depends on your specific needs and the nature of your API testing and development tasks. Postman shines for its user-friendly interface, making it accessible for both manual and exploratory testing, as well as quick API documentation generation. REST Assured, on the other hand, offers advanced automation capabilities, particularly when integrated into CI/CD pipelines, making it a strong choice for developers and testers comfortable with code-based testing.

Testsigma combines the ease of use and collaborative features of Postman with the automation capabilities of REST Assured, offering a comprehensive platform for automated testing. With Testsigma, you can create and execute API tests without the need for extensive coding, thanks to its natural language-based test creation approach using simple English. 

Frequently Asked Questions

Can we use REST assured with Postman?

REST Assured and Postman are separate tools designed for API testing, and they are not typically used together in the same testing process. Postman has its user interface and scripting capabilities, while REST Assured is a Java library for code-based automation. Depending on your testing needs, you may choose one or the other, but they are not typically combined within a single testing scenario.

Is Postman the best for API testing?

Postman is a popular and versatile tool for API testing, and it is often considered one of the best choices, especially for manual testing and quick exploratory testing. Its user-friendly interface and documentation generation features make it an excellent tool for a wide range of users. However, whether it’s the “best” tool depends on your specific requirements, team expertise, and the nature of your testing tasks. If you are looking for a power-packed automation testing tool, you should check out Testsigma.

Is REST Assured the same as REST API?

No, REST Assured is not the same as a REST API. REST Assured is a Java-based library specifically designed for automating the testing of RESTful APIs. It provides a framework and tools to make HTTP requests, validate responses, and perform various assertions. A REST API, on the other hand, is an application programming interface that uses the principles of Representational State Transfer (REST) and HTTP methods for communication between software components. REST Assured is a tool for testing REST APIs, but it is not an API itself.

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