API Testing: What ? Why ? How ?

What is an API ?
If you are someone in the IT field, you must have definitely heard of API. According to Wikipedia, an application programming interface (API) is a set of routine definitions, protocols, and tools for building software and applications. API works as an interface between two separate systems allowing them to interact with each other. A part of internal code is exposed to the outside world so that one program can communicate with the other one.

Why API Testing ?
Testing API is like testing any other interface of an software. According to Wikipedia, 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.

In Modern IT infrastructure, every other apps uses some form of API to connect between different apps; whether it may be something internal or an external app. Modern businesses rely on API to communicate between client and customers. High availability/up-time of an API has become an must in today's world. To ensure it, we need to make sure it works properly under different conditions.

How to Test an API (Basic) ?
API Testing includes making a request to API, confirm the expected/actual results and the time taken for the response to get delivered.

• Check how it works under typical conditions; testing its primary purpose. If it fails then, there is a serious bug which needs to detected and fixed.
• Stress Test helps an API to cope with unexpected or large no of outputs
• Also, we need to make sure how will the system react to sudden failures. It should have an proper exception handling and an active alert system.
• There are also tools that make this a lot easier. Some run on the command line like Curl, while some offer a more sophisticated user interface for configuring and stringing the calls, like Runscope.