Thank you for your useful information. Bellow is all that I understand about API & API testing:
APIs (Application Programming Interface) are used to integrate systems together. You can make data available for other systems to access via API or accept data from other systems. Usually API work similarly to the way any website works. A request is made from the client to the server and we get the response over the http protocol.
The following example can help you easy to imagine:
The best analogy can be a waiter in a restaurant. The Waiter takes the request (which is the order for food) from the customers and conveys it to the kitchen (which is our server) and gets the food (response) from the kitchen to the customers. APIs do the exact same thing. An API is the messenger that takes your request and tells the systems what to do and then returns the response back to you.
What is API Testing?
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, reliability, performance, and security. Since APIs lack a GUI, API testing is performed at the business layer. During the API testing the data is exchanged from XML or JSON through HTTP requests and responses. These are technology independent and will work with any of the programming languages and technologies.
There are 3 main reasons you should invest in API testing:
Testing the application early and without a user interface. The later you find defects, the more expensive they are to fix. API testing engages testers early in development lifecycle. With API testing you can start testing your application early even without a UI.
To come up with an awesome test automation strategy and reduce the test automation costs.
As we move up the pyramid, the cost involved in the creation and maintenance of test, the test execution
time, test fragility and test coverage keeps increasing. The automation pyramid preaches that you should
do much more automated testing through unit tests and API tests than you should through GUI based
- Agile Software development and reduced manual regression testing. Test automation has become a critical factor to maintain agility. So it is necessary for agile teams increase their level of API testing while decreasing their reliance on GUI testing. API testing is recommended for the vast majority of test automation efforts.
More information, Please refer here: https://guide2mobiletesting.blogspot.com/2017/01/how-api-testing-has-changed-way-we.html