API testing is a crucial part of web application development, as it ensures that the backend services and data exchange are working as expected. API testers are responsible for verifying the functionality, performance, security, and reliability of APIs using various tools and techniques. If you want to become an API tester or improve your skills, here are some key areas that you should focus on.
APIs can be classified into different types based on their architecture, protocols, formats, and standards. Some common types are RESTful, SOAP, GraphQL, and gRPC. Each type has its own advantages, disadvantages, and best practices for testing. You should be familiar with the main features and differences of each type, and how to choose the appropriate one for your project. You should also be able to use tools like Postman, SoapUI, or Insomnia to send requests and analyze responses.
Don’t needlessly retest your underlying web API framework. You’re doing this if you’re using a fake HTTP client or a tool like Newman or curl. Most frameworks enable you to write your presentation layer as a native function or method (in the programming language you’re using). You throw an HTTPException or return a model - and it handles translating it to HTTP. So trust your framework, I can assure you it’s already well tested by its author. Instead, unit test your controller/routes like any other public method (API). It’ll be faster, less brittle, and far easier to maintain. And inject your runtime dependencies for easier mocking!
Key skills got API testers : 1. Programming languages 2. API Protocols and formats 3. Testing tools 4. Automation Testing 5. Version control 6. Understanding of Http/https 7. Data handling 8. Security testing 9. Performance testing 10. Communication skills 11. Problem - Solving skills
Being able to write good test cases while keeping them focused on logic or business requirement rather than data is probably the most important skill required when writing tests for API. Over the last few years, maintaining API test has been the biggest challenge for me.
Key skills for API testers include proficiency in programming languages like Python or Java, understanding of HTTP protocols, knowledge of testing frameworks such as Postman or RestAssured, ability to create and execute test cases, experience with tools like Swagger for API documentation, and strong problem-solving skills. Additionally, familiarity with version control systems like Git and an understanding of security aspects related to API testing are valuable skills. Effective communication and collaboration with developers and other team members are also essential.
In the most cases, people seems to forget what type of APIs they are testing and developers forget what type of APIs they are building, for instance deciding on API type like POST, GET, PUT as they all play different roles in their own and tester should know if the developer has used proper type of API. RequestBody and RequestParam are not interchangeable, although the result is almost the same. But understand the basic difference and use cases.
API testing requires a systematic and logical approach to design test cases and scenarios that cover all the possible inputs, outputs, and behaviors of the API. You should be able to identify the test objectives, parameters, assertions, and expected outcomes for each test case. You should also be able to organize your test cases into test suites and test plans that follow a clear structure and naming convention. You should also be able to use tools like TestNG, JUnit, or PyTest to execute and report your test cases.
Além disso, é importante definir muito bem os cenários. Existe uma linguagem apropriada, que é bastante adotada para isso, chamada Gherkin, feita para pessoas que n?o s?o programadores escreverem seus respectivos cenários com facilidade. Esta e outras ferramentas podem ajudar bastante a estruturar o seu sistema WEB e aproximar o desenvolvimento das necessidades das partes interessadas.
Understanding all the test cases possible is very important. I may be over the line, but think of your users as a total moron, they will try to add alphabets in mobile number, also there are multiple scenarios where it is unpredictable like pin code in some countries only allow numeric values but can be alphanumeric for other countries. Understanding your users first before thinking of your scenarios.
Avoid extensive testing and concentrate on unit testing of the critical parts of the product first. If time allows, expand testing to other components of the software and/or use other testing methods, such as international or functional testing.
Scenarios are the core target of the endpoint, make sure you/team understand all the input and its formats and make the endpoint able to respond to them - Are the input prepared for special characters? - Are the HTTP core properly set for each response type? - Will input any file? How large the file can be? - How complex would be the operation?
Automating API testing can save time, effort, and resources, as well as improve the quality and consistency of your testing process. You should be able to use scripting languages like Python, Java, or JavaScript to write code that can perform various API testing tasks, such as sending requests, validating responses, handling errors, generating data, and logging results. You should also be able to use frameworks like RestAssured, Requests, or Mocha to simplify and enhance your automation code.
When working with Java, there is a scripting language groovy which can help you achieve automation testing , it is the same syntax style as Java and is very easy to understand for Java developers. Although it cannot replace Java but it will help you achieve automation testing, there are external tools also available like Mockito framework, JUnit which helps in integration or unit testing etc.
API testing automation helps streamline processes and ensures efficiency. The ability to automate API testing not only accelerates the testing lifecycle but also enhances accuracy and repeatability. One tool for achieving automated API testing is Cypress. Known primarily for its frontend testing, Cypress seamlessly extends its capabilities to API testing, allowing testers to create comprehensive end-to-end tests that span both frontend and backend components. With its intuitive syntax and robust features, Cypress empowers testers to automate HTTP requests, validate responses, and execute assertions, providing a unified testing environment. This expedites the identification of issues and also facilitates quicker feedback loops.
Continuous Integration and Continuous Delivery (CI/CD) is a defacto approach to automate API testing. Git hooks are a good way to run some quick and cheap tests before committing code into Git.
API testing can encounter various issues and errors, such as incorrect parameters, invalid formats, broken links, authentication failures, or server errors. You should be able to use debugging and troubleshooting techniques to identify the root cause and resolve the problems. You should also be able to use tools like Fiddler, Charles, or Wireshark to monitor and inspect the network traffic and API calls. You should also be able to use tools like Postman Console, Chrome DevTools, or Visual Studio Code to debug and trace your code.
API security is essential to protect the data and functionality of the web application from unauthorized access, manipulation, or attacks. You should be able to test the API security aspects, such as authentication, authorization, encryption, rate limiting, and error handling. You should also be able to use tools like OWASP ZAP, Nmap, or Burp Suite to perform security testing and penetration testing on the API. You should also be aware of the common API security risks and vulnerabilities, such as injection, broken authentication, or misconfiguration.
One way of testing is passing wrong authentication values or even not passing authentication values and check it returns data or not! if it returns, the api is not secured! Also we can check the same token is valid after few days by testing using the same token but we have to store this token and its timestamp in a local or remote storage
API testing is a dynamic and evolving field that requires constant learning and adaptation. You should be able to keep up with the latest technologies and trends in API development and testing, such as microservices, serverless, GraphQL, OpenAPI, or Swagger. You should also be able to learn new tools and frameworks that can help you improve your API testing skills and efficiency. You should also be able to follow the best practices and standards for API testing, such as RESTful API Testing Strategy, or API Testing Pyramid.
When Use: REST API: You need stateless communication, and your application can work with standard CRUD operations. gRPC: You need high performance, and efficiency, and want to define APIs using Protocol Buffers. Suitable for microservices architecture. GraphQL: You want to give clients more flexibility in requesting specific data, avoiding over-fetching or under-fetching of information. WebSockets: Real-time communication is essential, like chat applications, live updates, or collaborative editing. SOAP (Simple Object Access Protocol):You are working in a legacy system or require a strict, standardized protocol with built-in security Webhooks: You want to receive real-time updates or notifications when a specific event occurs.
These other skills could collectively contribute to an effective API testing strategy: - Data formats: Understanding of data formats commonly used in APIs, such as JSON and XML, and the ability to validate and manipulate data in these formats. - Testing methodologies: Familiarity with different testing methodologies like unit testing, integration testing, and end-to-end testing in the context of APIs. - Security testing: Knowledge of API security concepts such as authentication, authorization, and encryption, as well as experience in testing for security vulnerabilities. - Communication and collaboration: Strong communication skills to work closely with developers, product managers, and other stakeholders to understand requirements.