API testing is a type of software testing that involves testing application programming interfaces
(APIs) directly and as part of integration testing to determine if they meet expectations for functionality.
Since APIs lack a GUI, API testing is performed at the message layer. API testing is now considered.
critical for automating testing because APIs now serve as the primary interface to application logic and because GUI tests are
difficult to maintain with the short release cycles and frequent changes commonly used with Agile software development and DevOps.
So, API Testing supports validation of Functional Testing but does not replace it. API Testing does not cover the complete Functional Testing which covers business scenarios – test cases have to prepared for the same and executed separately. Single API could be called in several functionalities in the Web Application, validation of Single API indirectly validates several Functional Test Scenarios. Functional Testing focus more on end user perspective whereas API Testing validates the intermediate stage. It is more like unit Testing to validate the processing using Input parameters and outputs Parameters. In an API test, data is exchanged using XML or JSON.
Compared with graphical user interface (GUI) testing, application programming interface (API) testing provides several key benefits, each of which can improve the coverage of test cycles, conserve resources, and result in faster, more efficient releases.
Benefits of API Testing
Test for Core Functionality : one of the key benefits of API Testing is access to the application without a user interface. Testing the core, code-level functionality of the application provides an early evaluation of its overall build strength before running GUI tests. This helps expose the small errors that can fester and become larger problems during GUI testing.
Language-Independent : In an API Test, data is exchanged using XML or JSON. These transfer modes are completely language-independent, allowing selection of any core language when pursuing automated testing services for the application.
Time Effective : API Testing is far less time consuming than functional GUI testing. In GUI testing, webpage elements must be polled, which slows down the testing process immensely. APIs can achieve 80 % of time saving to validate the core functionality of the application.
Easy Integration with GUI : With API Testing, highly integratable tests are possible. This is especially beneficial if functional GUI testing are executed following API testing.
API Testing Automation Tools
Analysis
There are 2 types of APIs widely used namely SOAP (Simple Object Access Protocol) and REST (Representational state transfer) but about 80% of APIs are of type REST.
REST APIs are HTTP-based web services that adhere to REST architectural constraints. These days, systems that talk to each other over the web, mostly use REST APIs.
Tools Selection
With the emerging trends and technologies, a number of automation tools are available in the market. Therefore, identification of an appropriate tool best supporting the application under test gains prominence. Tool evaluation is inevitable for selecting the automation tool that meets the project expectations.
Soap UI
Postman
Rest Assured
Fiddler
API Test Automation Framework
The Components being used in the framework and their purpose are explained below :
Rest Assured : REST Assured is a Java library that provides a domain-specific language (DSL) for writing powerful, maintainable tests for RESTful APIs.
Cucumber : Cucumber is a tool for running automated acceptance tests written in a behavior-driven development style. One of its wonderful main features is the ability to execute plain-text functional description as automated tests.
Java : is a object oriented programming language. It has become a language of choice for providing worldwide Internet solutions because of robustness, ease of use, cross-platform capabilities and security features.
Junit : Junit is widely adopted by organizations around the world for performing unit testing in Java programming language. JUnit has become a standard for testing in Java programming language and it is supported by almost all the IDE’s.
Javax.mail : With the help of Javax.mail, Framework is designed to send e-mail containing execution reports to users automatically. It gives the option to execute the suite overnight and after the completion of execution, the report would be in the email inbox for our action.
Maven : Maven is a build management tool that helps us to manage the libraries of the framework. It also helps us in continuous integration.
Jenkins : is utilised for continuous integration
Log4j : is used for capture execution logs.
POI : is used for test data management and other configurable items.
