What is API testing and why is it important?

API testing is a crucial aspect of software development that ensures the proper functioning and reliability of application programming interfaces (APIs). APIs serve as the communication backbone between different software components, enabling seamless data exchange and functionality integration. API testing plays a pivotal role in verifying that APIs meet the expected standards for functionality, reliability, performance, and security.

API testing instills greater confidence when evaluating the business logic aspect of a system. This approach is strongly endorsed during the initial phases of development, as it does not necessitate a user interface or frontend. Additionally, API testing is rapid, sturdy, encompasses a broad spectrum, and excels at uncovering crucial and severe application issues.

API testing should considered with below test coverage: 1. Functional: Should include integration testing with below validations: 1. Schema validations - regex field validations for 400 http codes 2. Business validations - covers integration testing with business scenarios in place gives 422 http codes 3. Technical validations: network connectivity, API gateway responses gives 500, 504 http 2. Non Functional Testing: This is equally important in order to get the API performance and how secures it is. So testing should cover: 1. Performance & Load testing: Cover all the aspects and different types.of performance testing for eg. Stress, scalability, etc. 2. Security testing: Cover all aspects and different types.of security testing like fuzz

APIs (Application Programming Interfaces) are protocols for building and interacting with software applications. 1. An API defines methods for a client to request services from a server. It processes requests, performs actions like database queries, and returns responses, such as data or confirmation messages. 2. APIs ensure different software components can exchange data in a standardized way using common protocols like HTTP and formats like JSON or XML. 3. 3. They often include security measures like authentication to protect access. In summary, APIs are essential for integrating diverse systems, enabling functionalities like cloud services, and facilitating microservices and service-oriented architectures in software development.

How do they work? Request: An application requests specific information or functionality for another application, such as retrieving data or performing a specific task. Processing the request: The receiving application processes the request, interprets it, and performs the necessary actions. Continuing to the example of amazon Response: After processing the request, the application sends a response back to the request process. This response can be a request for data, a confirmation of the action taken, or an error message if something went wrong.

API tests use extreme conditions and inputs when analyzing applications. This helps remove vulnerabilities and guards the app against malicious code and breakage. API tests can be integrated with GUI tests. For example, integration can enable new users to be created within the app before a GUI test is performed.

API Testing is similar to testing the engine of a car. The exterior and interior can be beautiful but if the engine fails, then we haven't built anything really. Testing the API ensures the logic ,validations and functionalities are implemented properly for an almost seamless integration with the UI

API testing is basically to test the backend of an application.In my opinion any application should have API first approach whereby we make sure the logics and functionalities of the application is tested well in advance before integrating with UI. There are many benefits with API first approach 1. Not only functionality, we can also test the performance, security, usability. Exploratory testing is also possible 2. It is easy to test API.Maintenance cost is low.Automation suites for APIs can be easily built and maintained 3. With API testing quicker release and faster feedback is possible. Functional defects can be identified at the earlier stage 4. We can achieve in sprint automation and shift left testing with api first test approach

- Easier to shift left - Better test coverage - Lower maintenance - Faster bug fixes - Reduced testing costs and there are other benefits as well like contract testing helps lot in the integration

API testing is being done to ensure it meet expectations regarding the functionality, reliability, performance, and security of the application. And API testing could be performed before the GUI implementation of the module. 1. Access to the application without user interface 2. Core functionalities of the application will be tested and evaluated early before the GUI tests and early identification of issue helps making application better. 3. API testing is faster and time effective compared to GUI testing 4. Easy to integrate with GUI

Challenges - Lack of documentation - Requirement is not clear - Integration implementation delay - Contract mismatch - Lack of JSON knowledge - Frequent Schema changes - Data formatting - Test implementation - Service downtime

Challenges in API testing - Lack of knowledge (need to know more about system architecture, endpoints, at times Database and table details too). - Testing must be done for tailoring to the end user like B2B flows or B2C flows. Who is going to consume the APIs whether your internal dev team or external parties. - sub-systems or third party systems downtime can cause delay in completing testing. - Changes may be more frequent than client app testing.

API testing presents several challenges. APIs can be complex, with numerous endpoints and parameters, making test case design and management challenging. They are subject to change, requiring test suites to adapt. Managing and maintaining test data for APIs can be intricate, as they often interact with databases and external systems. Security testing, involving authentication and authorization, demands specialized expertise. API testing relies on external services, affecting test stability. Ensuring version compatibility and backward compatibility is complex. Inconsistent or outdated API documentation can hinder testing efforts.

API testing presents notable challenges that hinge on the proficiency of testing teams. It necessitates a deep understanding of not only the API's design but also its intricate functionality, logic, and the tools and frameworks employed for testing. Technical skills are indispensable when testing complex scenarios, data formats, protocols, and parameters. To surmount these challenges, a comprehensive test strategy must be devised to evaluate multiple facets of APIs, encompassing functionality, performance, security, reliability, documentation, and usability. Furthermore, close collaboration between developers, testers, and other stakeholders is vital to ensure effective testing across diverse components, systems, and platforms.

Complexity: APIs can be complex, with many different functions and options. Testing all of them can be tricky. Data Handling: Managing and validating data sent and received by APIs can be challenging, as it needs to be precise. Changes: APIs can change over time, and updating tests can be a headache. Documentation: Sometimes, API documentation is not clear or missing, making it hard to know how to use the API.

API testing encompasses various types tailored to assess different aspects of an API's functionality.Functional testing focuses on validating the API's expected behavior, while unit testing drills down to test individual components. Integration testing verifies how well multiple APIs interact with each other. End-to-end testing ensures the complete workflow involving APIs, dependencies, Load testing assesses an API's performance under heavy loads, and security testing examines authentication, authorization.Negative testing checks how the API handles erroneous inputs. Regression testing aims to prevent the introduction of new defects with changes and stress testing pushes the API's limits. Performance testing optimizes speed and scalability.

- Validation Testing - UI testing - Functional Testing - Load Testing - Contract Testing - Security Testing - Fuzz Testing - Negative Testing - Regression Testing - Integration Testing

API testing involves a range of testing approaches and strategies to ensure the reliability, functionality, security, and performance of APIs. Here are some of the common types of API testing: 1. Unit testing 2. Functional testing 3. Integration testing 4. End-to-End Testing 5. Load Testing 6. Security Testing 7. Penetration testing 8. Fuzz Testing 9. Stress testing 10. Negative testing 11. Mock testing These various types of API testing ensure that APIs are thoroughly tested across different aspects, covering functionality, performance, security, and integration, leading to robust and reliable systems. The selection of specific testing types often depends on the application's requirements, goals and the level of testing needed for the API.

There are various types of API testing, each focusing on different aspects of the API: Functional testing: Verifies that the API behaves as expected for various inputs. Performance testing: Evaluates the responsiveness and scalability of the API under load. Security testing: Identifies and mitigates security vulnerabilities in the API. Integration testing: Ensures that the API works correctly when integrated with other components of the system

There are lot of tools and frameworks available in market Tools : Postman, SOAP UI, Swagger, Insomnia, JMeter, WireMock, Apigee, Hoppscotch, etc.. Frameworks : Rest-Assured, Karate, Rest Sharpe, Chai, Mocha, Jest, etc..

There are several tools and frameworks available for API testing catering to different needs, environments and preferences: Postman: Supports manual and automated testing. SoapUI: Soap-based web services, REST APIs. Allows functional, load testing REST Assured: Java-based library, used for RESTful API testing. Offers simple and natural syntax JUnit/TestNG: Java-based testing frameworks. Used for Unit testing and API testing Swagger/OpenAPI: Defines the structure of the API and provides tools that generate client libraries and testing frameworks automatically Karate: Open-source, combines API test automation, mocks, performance testing and UI automation in a single framework. Uses Gherkin language JMeter: load testing and API testing

API testing tools and frameworks play a crucial role in ensuring the functionality, reliability, and performance of APIs. Here's a brief description of some of the prominent tools and frameworks used for API testing: Postman, Swagger, Rest Assured, Junit, SoapUI, Karate, Chai and Mocha, Pytest, Cypress, Apache Jmeter, WireMock, Newman

Tools - Postman, Swagger, SoapUI (pro & free), Insomnia, Stoplight (paid) For Automating API tests: - Postman - SOAPUI - Jmeter - RestAssured (framework) - Karate

Numerous tools and frameworks can be used for API testing, including: Postman: A popular tool for designing, developing, and testing APIs. SoapUI: A comprehensive tool for testing both SOAP and REST APIs. JMeter: An open-source tool for performance testing of APIs and web applications. Katalon Studio: A versatile automation framework for testing APIs, web applications, and mobile apps.

API is an acronym for Application Programming Interface. In software application (app) development, API is the middle layer between the presentation (UI) and the database layer. APIs enable communication and data exchange from one software system to another. API testing is a software testing practice that tests the APIs directly — from their functionality, reliability, performance, to security. Part of integration testing, API testing effectively validates the logic of the build architecture within a short amount of time.

Security testing is not considered as part of API Testing in many organizations. Include Security testing and find API Vulnerabilities at the beginning of Test cycle.

API testing makes sure communication channels work as expected. 1. Reliability: It ensures that software components can exchange data reliably, which is vital for the overall functioning of applications. 2. Accuracy: API testing checks if the data sent and received is accurate, preventing errors in data processing. 3. Security: It helps identify vulnerabilities in how data is transmitted and received, which is crucial for safeguarding sensitive information. 4. Efficiency: Efficient APIs improve the speed and performance of applications, as they exchange data smoothly. 5. Integration: It helps different software systems work together seamlessly, which is essential in today's interconnected world.

API testing plays a crucial role in upholding the dependability and effectiveness of applications that depend on external services, and it also ensures the smooth integration of diverse software components. By detecting and resolving issues before they affect end-users, API testing becomes an indispensable element of the software testing process.

API testing, is the process of evaluating and verifying the functionality, reliability, and performance of anAPI. APIs allow different software components or systems to communicate and interact with each other, making them a crucial part of modern software development. API testing is important for several reasons:Functionality Validation,Data Integrity,Error Handling,Security,Performance and Scalability,Compatibility,Documentation,Regression Testing and cost reduction. API testing essential for ensuring reliability, security, and performance of APIs, which are the building blocks of modern software applications and services. It helps maintain the integrity of data and ensures that different software components can work together effectively.