How do you automate API testing and what tools do you use?

API testing is the process of verifying the functionality, reliability, performance, and security of an Application Programming Interface (API). Unlike GUI testing, which focuses on the user interaction with the application, API testing concentrates on the business logic layer, ensuring the API behaves as expected. This includes validating endpoints, parameters, request methods (GET, POST, PUT, DELETE), and expected responses. API testing is crucial for ensuring accurate and efficient communication between different systems or services, providing a solid foundation for application functionality.

Automating API testing involves leveraging specialized tools and frameworks like Postman for user-friendly interface-based automation, Rest Assured for Java-centric testing, and Newman for command-line execution of Postman collections. Swagger tools, supporting the Open API standard, are useful for describing and automating RESTful APIs. Additionally, script-oriented approaches using JUnit or TestNG with HTTP client libraries, tools like Insomnia for script-based scenarios, and Cypress for JavaScript-based API testing offer versatile solutions. The choice of tools depends on factors like team expertise, programming languages, and specific API requirements, ensuring efficient and reliable automation of API testing processes.

API testing is the process of confirming that an Application Programming Interface (API) is working as expected. It involves checking the functionality, reliability, performance, and security of the programming interfaces. Since APIs tend to be consumed by other services, their performance is crucial to the success of the layers built on them. Regularly testing of APIs thus assures the needed quality.

API testing can be automated using tools like Postman, SoapUI, or Rest-Assured in conjunction with programming languages such as JavaScript, Java, or Python. Automation involves writing scripts to send requests to APIs, validate responses, and perform assertions on data. These tools offer features like parameterization, environment management, and comprehensive reporting to streamline the API testing process.

Automate API testing with Postman using its intuitive GUI and scripting capabilities in JavaScript. Use Newman for command-line execution and integration with CI/CD pipelines. Alternatively, REST Assured is a Java-based framework for automated API testing, offering robust capabilities for HTTP requests, assertions, and JSON/XML validation. Postman is ideal for quick setup and collaboration, while REST Assured suits Java environments and complex validations. Both ensure efficient API testing with distinct strengths in usability and integration.

**Define Scope and Objectives** : Clarify endpoints, methods, and scenarios for testing. **Select Tool/Framework** : Choose based on requirements, preferences, and budget. **Develop, Execute, and Improve** : Write test cases, execute, monitor, and refine based on feedback for optimal results.

Automating API testing involves using scripts and tools to automatically execute a series of tests on an application's APIs. The process starts with defining test scenarios, which include various combinations of inputs and expected output validations. Automated scripts simulate requests to the API, verifying if the responses are as expected. Automation not only speeds up the testing process but also ensures consistency and repeatability, allowing for frequent test execution during the development cycle, especially in continuous integration (CI) and continuous delivery (CD) pipelines.

To create automated tests for APIs, you will need tools that integrate easily with your development environment. To illustrate, a developer making use of Python could make use of the "requests" library in addition to pytest. Other tool include Postman, Apigee, REST-assured, SoapUI, and others. When the choice of tool is made, the developer then makes call to the API endpoints and validate the response of the call against the predefined requirements.

Automating API testing involves steps like identifying endpoints, crafting test scenarios, and selecting appropriate tools like Postman or Rest Assured. Write test scripts to send requests, validate responses, and assert results. Leverage frameworks like BDD or TDD for structured testing. Execute tests regularly, integrating them into CI/CD pipelines for continuous validation. Finally, analyze results and iterate for enhanced test coverage and reliability in API automation.

From my side, I would highlight two solutions: Postman and Playwright (maybe with CodeceptJs) Postman Advantages for API Testing: 1.User-Friendly Interface. 2.Collaboration Features. 3.Pre-built Tools and Integrations. 4.Environment Management. 5. Community and Support. Playwright Advantages for API Testing: 1. Code-Driven Testing. 2. End-to-End Testing. 3. Multi-Browser Support. 4. Powerful Assertions and Debugging

Which tools can be used depends really on the requirement and the resource available. 1. If you want a bit of less coding, user friendly, quick testing and want to use only one tool for both manual and automation API testing - POSTMAN in conjunction with NEWMAN could be your choice. 2. If you want to build an end-to-end custom testing framework/solution for the API testing - RestAssured or Playwright would be best. 3. If you your requirement is to perform load/performance testing for APIs - Go with JMeter, the ultimate winner in this category.

It might sound counter intuitive, but a great tool for API testing that we implemented on my company is Playwright. But why would someone use a UI testing tool for API testing? Because Playwright is able to do many things that other API testing frameworks do, and more. Playwright allows you to use object oriented programming within your API tests. You can assign a variable to the GET,PUT,POST,DELETE, and then use that variable to get information about the response that the server was given. Then you can make several assertions on an API response without a crazy amount of chaining. One other positive point is to reduce cognitive load on the team. It's much easier to have to learn only 1 framework between UI and API automation.

Several tools are available for API test automation, each offering unique features and benefits. Postman is a popular tool with a user-friendly interface for creating and executing API tests, along with automation capabilities through collections and scripting. Cypress, known for front-end testing, also supports API testing, allowing integration with interface tests. Robot Framework offers a keyword-driven approach to writing test cases, useful for teams preferring more readable syntax. JMeter is primarily geared towards load and performance testing but can also be used for functional testing. Finally, RestAssured is a Java library that facilitates API testing in Java-based environments.

While tools like Cypress, Selenium, or Playwright may be used for API testing; they are overkill and too bourgeois. It is more suitable to use tools such as Python's requests or Postman to make API requests for testing purposes since they are generally faster.

I strongly recommend against choosing separate tools for different types of testing. For example, using API testing tool X, web testing tool Y, and mobile app testing tool Z adds unnecessary costs and maintenance work to the business. For QA processes, it's advisable to opt for a global tool that serves as a one-stop solution, encompassing test case management, defect management, and automation. Currently, QAautoMATER provides all these solutions under one platform.

When automating API testing, it's essential to consider not only functionality but also security, performance, and maintainability of the tests. Security is critical, especially for APIs handling sensitive data; thus, including tests for authentication and authorization is crucial. Performance testing helps identify bottlenecks and assess the API's scalability. Additionally, it's important to maintain good test coverage, ensuring all critical functionalities are validated. Proper documentation of test cases and maintenance of test scripts are essential to ensure the automation remains effective over time, making it easier to identify and resolve issues.

Testing APIs with Katalon is simple. You can build tests for UI and web services (like SOAP, REST, GraphQL). Easy to learn and well-organized, even for non-coders. You can run tests one by one, all at once, or schedule them. Plus, Katalon integrates with CI/CD tools like Jenkins or Azure DevOps. And you can mix and match API tests with other tests for reusability.